1) Mess around with the beginning. Play around with it, look at it from a few different angles until you find the right one. It's the first thing people will read so it better be good.
2) Try to keep the same voice throughout.
3) Don't listen to music while writing if it just distracts you.
4) Stay within your preffered genre, but do any research you can. Read those books in your genre, especially new releases.
5) ...But read old favourites too. They can be inspirational.
6) Remember you're not the only writer who ever lived. Talk to other writers if possible.
7) Know the rules of writing before you decide to break them.
8) Computer's good for a quick flow of ideas, i.e. must write must write now now now typey typey. Use pen and paper as well though; the slower pace will make you concentrate more on your words and good stuff will come out.
9) ALWAYS. USE. SPELLCHECK. Militalia isn't a word.
10) Don't, repeat don't, rush the ending.