Writing is an extremely solitary profession, there are some resources for writers (books, conventions, classes), but little in the way of a community for sharing and discussing ideas. Further, I've found 90% of aspiring writers encounter the same troubles, troubles which can be overcome if they could arm themselves with just a little knowledge and a few tips.

Writing is a Skill:

    Writers are not born great. They put a tremendous amount of hard work into learning their craft. Further, most people think that graduating from high-school or college prepares you to be a great writer (you had 4 years of English classes, right?), or that if they're reasonably intelligent they can write a good novel right out of the gate. It simply isn't true. Steven King was a professional writer, trying to get published, for 7 years before his first book "Carrie" was bought. Becoming a writer is rewarding, but also a lot of hard work.

Even excellent writers write badly:

    Books you see in the store are usually representative of an author's best work, not their average or worst work. For every story an author publishes he's got five or ten which just didn't cut the mustard.

Write every day:

    Even if it's only for a few minutes. If you're a writer, then write. It can be short stories, pieces of stories, or scenes from your childhood. Write whatever you like, just write. It's the only way you'll get better, and if you don't do it, you'll get writer's block more often, and your skills will atrophy.

Learn the rules of writing:

    Far too many people believe that because writing is an art, there are no rules. These tend to be people who simply don't know the rules, and are too bothered to take the time to learn. Or they think they're so good that they're above learning the rules. If that's true, you're better than Hemingway, because he believed in the rules. Yes, the masters all broke many rules, but they knew which rules they were breaking, and broke them with purpose.

Learn your grammar:

    Most aspiring writers don't bother with the rules of grammar. They figure they're storytellers, and grammar is someone else's problem (an editor or publisher). However grammar is your single most important tool. Your story could be the greatest story ever told, but if nobody can read it, who cares? If a reader is tripping over your language, they won't know what you mean.

Be Patient:

    You've got all the time in the world to learn your craft. Just keep at it, you'll get there. It can be tough, but it's more than worth it. This is a career, and like most, you need to be focused on the long haul.

Your best friend is a first draft:

    Everybody (everybody) uses drafts. Most inexperienced writers think that they don't need to. Yes, it's a pain to re-write your novel, but a true 300 page book is far too large to keep all in your head at once. Make your first draft about finishing, not about doing a good job. As strange as it may sound, you don't know what you want to say till you can see what you've written. Until you finish that draft, you can't see the whole book (this is why painters usually sketch their paintings first- to make sure everything will fit and look right. Nobody expects a painter to start from the top of the canvas and paint strait to the bottom. A painting is done in pieces. So is a book). Promise yourself that you'll never show anyone your first draft. Then you can let it be as bad as you want, and you can just finish it, and see what is the story that you're really trying to tell.