I've been asked a few times now for tips on novel writing so I'm writing this as a reference. This way, I can go back and add anything I forget.
Writing is fun, and it's a good thing to be interested in if you have the patience. If you have an idea you want to write a story about, just write it. Just do a section or a chapter at a time and then edit it to your liking.
I was asked once “How do you write so well?”
Honestly, I'm not that great. But to get to the level I'm at now has taken four years of sparse practice.
I started writing a story when I was about fourteen that I decided to make into a novel called Dymecia. It definitely had it's failings and so I scrapped it once I was at about 51,000 words. Yes, I know, I had achieved novel length. Which is why there was too much to just edit. In fact, I just checked the file on my computer and the date the file was last modified was September 9, 2006.
Now, to list the fallacies of Dymecia which I have learned from:
Characterization
Plot
Logic
Dialogue
That's a lot of problems when you consider that characterization can mess up dialogue horribly and erratic logic will lead to a confusing plot.
Another question: “Where do you get your determination from?”
I responded, “You just have to want it bad enough.” By that, I mean that you have to have the patience and the drive to continue your story. An outline helps too, but I'll touch on that more later.
In fact, with Dymecia, I went so long without adding anything to the story that I had to read back to see where I left off. With Disciple, my new novel-in-progress, I date the day of completion of a chapter, they go October 19, 2006, January 19, 2007, and I won't list them all, but just know that I took a three month break between chapter three and four. So I'm really not that determined. Dymecia took three years for me to not finish it.
Ok, now I'll get into the real meat of this deal.
Characterization
This should be the most important element in your story. The characters are your actors and you are their creator. Yes, writing is a little bit like playing god on paper, that's part of the thrill of it 
Here's a quote that I've referenced a lot because it helps me a lot:
"With straightforward narrative you may be able to create in the reader's imagination a visual image of a character, but the character will spring to life only when he is put to the test, when he is forced to make a decision and act." -James N. Frey, How to Write a Damn Good Novel
What this quote means is that you can describe what they look like easily. If I wanted to describe Coda, a character from Disciple, I'd say:
Coda was a tall, strong-looking man. His face is weathered by not only age but the sadness of his past. His left hand is marred with a line of wrinkly pitch black skin; a scar of the black mist. He wears a silver pendant of a star and a crescent moon around his neck—inherited from his father—and a small white jacket. His medium-length jet black hair contrast with the luminosity of his blue eyes.
Now you know what he looks like, right? When people write their characters, they almost always start with the visual image. Not a bad idea to be able to see the character when you write about them. But, alas, anime and games like Final Fantasy have caused people to want to make their characters look as cool as possible. However, appearance is of little importance in a book.
Which brings me to my next little tip on characterization: characterization. Ha ha, I made a funny...
Excuse my silliness, please.
But seriously, characterization has very little to do with the appearance of your character. It is who they are and how they develop. If I wanted to tell you who Coda is (rather than tell you what he looks like) I would say:
Coda was a soldier of Sendeau. He is very detached from people, trying his best not to give away the details of his past. He hates living on the homeships about as much as he hates the black mist. His favorite thing to do to forget his worries: drink. He wouldn't go so far as to admit to being an alcoholic, but others might...
Now you get an idea of who he is. I know these little narratives aren't very well-written, but I just kind of did them off the top of my head.
Who your character is will affect how they take on challenges and interact with others. Will they run away from the face of danger, or will they fight? Will they pull out a tire iron on the person who gave them a fender bender, or will they try to solve it reasonably?
This is the next part of the quote, the part about making a decision and acting. First, in case you haven't learned this in English yet or you just don't pay attention, I want to just give a little list of the different types of character:
Round: The person is well-rounded and can be seen as a real person. Usually an important person in the story.
Flat: Not well-developed. A very generic character. About as important as an extra in a movie. No main character should be flat, this is usually someone like the person who gives your character the ticket to go to the movies.
Dynamic: Any character that changes throughout the course of the story. This is the character that pulls out the tire iron in the beginning of the book and learns to work things out reasonably by the end of the book.
Static: A character that stays the same. Think about the “snow channel” on your TV. It's just a static signal, and the picture never changes. This would be if the character was still resolving his minor accidents with the large metal object at the end of the story.
Protagonists should always be round and dynamic. It is also a good idea to keep the antagonist this way too.
Your characters should grow throughout the story. They should learn, change, all that good stuff. The way your characters act in certain situations affects the way conflicts are resolved.
It also helps, if your character has a long history, to write out a biography of the character.
Okay, I'm done talking about characterization for now, but I may come back and add more later. There's a lot more to it that I forgot to mention.
Plot
The plot's not as important as the characters? *gasp* E-gad! OMG! ETC.!
Not in my opinion. What's a good story without vibrant characters? Wouldn't you want to make a character that people will learn to love, to want to be, to want to meet, to hate? You want to evoke feelings from the reader, it is what proves that you have written the characters well and that they really like the book.
However, I will admit, the actors would be nothing without a stage. But a stage with amateur actors is just as useless as an empty stage. Okay, I'll end this metaphor now.
I can help you with your plot only as much as I can help you with your imagination. Which basically means I'm somewhat useless in creating your plot, but why would you want me to write your plot for you anyway?
Stories are basically one big plotline growing off of one main conflict leading up to a climax, but that one plotline can consist of many other subplots with their own conflicts and climaxes.
Now, you probably have an idea for a story, but now you need to expand on it. Once again, I'll use Disciple for my example.
A world has been consumed by a fatal black mist and the people of the lands have taken to the skies to avoid it. Now the characters must find the source of the black mist and destroy it.
There's my one big plotline with the central conflict and the last two words seem to hint at the climax.
Now I must write ideas for chapters, which will contain their own conflicts and climaxes and resolutions. This is where the outline comes in. Many people try writing without outlines. The lack of an outline was a huge contributor to the craptastic ending that Dymecia had. What was the ending? The trash and the knowledge that I've learned from a 51,000 word mistake.
Now, I know what you're probably going to say; “But I just write the story without an outline because I can just do it like that. It's like story's writing itself! zomg!!1”
Please don't be one of those people.
An outline is easy to make and it rids of the problem of writer's block. Basically, all you need to do is write out the chapter names and then expand. Example:
Chapter 1
Character A wakes up
Gets a phone call from character B
B presents A with a conflict
Chapter 2
A decides to help B with the conflict.
I think that's a good enough example. Outlines help a lot because when I'm done with a chapter, I know where to start on the next one. And I even know exactly what will happen.
Make sure that your logic matches up within the story. If something strange happens, you need to be able to explain it to someone. Bad logic can lead to a bad plot.
Conflict
I've already touched base on this one, but just to clarify, the example of the person with the tire iron was conflict. Conflict happens to us everyday in the real world and we learn to cope with it in one way or another. You should treat your character as a real person as well. Fire them from their job that they've had for eight years and see how they react. Will they explode? Kill themselves? Punch their boss? Or will they try to find another job?
Whatever you make them do changes them and makes them grow, makes them real, and makes them dynamic.
If I were George W. Bush, I'd probably have said something like, “You see, characters are like play-doh...” I think you get my drift.
Dialogue
Make your characters seem real through dialogue. Not only should you make dialogue real, make it interesting and make the topics of conversation relevant to the story.
Bad example:
“Hi, what's up?”
“Not much, just chillin'.”
“That's cool, do you want to hang out today?”
“Sure, but I've got to eat first.”
“Okay, so do you want to meet up around two O'clock?”
“Sure thing!”
Sounds like a conversation you'd have with your friends on the phone, right? Now you see how boring your life really is from the third person's perspective 
Anyways, dialogue should be more in depth and, like I said, relevant to the story. This conversation has no conflict other than the fact that the person needs to eat. Now, if the conversation later on, at around two O'clock, were like this:
“Where are you?”
“Who is this?”
“[Character A], where's [Character B]? Is he all right?”
“He was in an accident just a little while ago. He didn't have any identification on him so we tried to use his phone to find out. You're the first person we've gotten a hold of.”
“An accident? Is he going to be okay? Where is he!”
“We're taking him down to the hospital now. If you could come tell me his name and come down to identify him you would be a big help.”
“Identify him! Is he...?”
Here in this scene we can see the character change. We can see how Character A reacts to the news. At first, she seems a bit impatient, right? Then she is confused by who is on the other line. Then she gets worried, and then she is faced with the dilemma that her friend might be dead or dying.
That should be enough information to get you by on the dialogue of your story.
The next two things are solely for if you are writing a fantasy novel:
Know the world you are working your story around. If you build an epic world, you must know just about every detail within it. You are the god of the world you have created, it wouldn't make sense to not know every thing about it. Know the people, the places, the geography, everything.
Have specific rules of magic. Every story has different rules to magic. In Harry Potter, they just have to practice the spell and then can use it forever. In the Dragonlance series, mages must study all the time so they can use their magic. When they use a spell, they forget how to use it and must relearn it. It also drains their energy, which sets the limit to how much they can use. I've actually written a thing about how magic works in my story, so you can look at that if you want an idea. Rules of Magic in Seilice
That's all I can think of for now. I hope this helps. I can't really help with sentence structure and grammar unless you write something, in which case I'd be happy to do so.
Oh, and if you want more help from the place I got it, buy or check out "How to Write a Damn Good Novel" by James N. Frey.
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