The writing process: some practical tips (in no particular order)
1. Get accustomed to writing many drafts and throwing things out. Use the first draft to find out what you think, and the second to begin making your ideas clear to an audience.
2. When you first sit down to write, start with whatever you can, wherever you have something to say. (You can move it later to where it actually belongs.)
3. Don't stop and grope for the best possible word. Use a word that's not very good or put in a cue to yourself to hold the place. You'll come back to it and find a better phrasing next time around; in the meantime, you won't lose your train of thought.
4. Leave yourself time to stop and take your mind off the subject: nap, walk, incubate. A lot of writing happens when you're not actually at the keyboard.
5. It's okay to use "I". Really.
6. It's okay to say what you really mean, directly and in plain English. It is not good for the public's health to use pretentious language in order to sound "classier" or more "academic" or more "professional".
7. It's okay to take a position--more often than not, your instructor will want you to. Just make sure you show how you got there.
8. Start every paper with a clear statement of the problem you're addressing and your purpose in addressing it, but don't expect to be able to write a good introduction until you finish at least one draft.
9. Be explicit: as you revise, show the connections you're making from one idea to another, one paragraph to another, one section of the paper to another.
10. Read your draft out loud and listen for awkward wordings, convoluted or incomplete sentences, abrupt interruptions of "flow," and other problems. If you hear yourself gasping for breath, something's wrong.
11. Never hand in your first attempt at writing a paper, even if your instructor asks you to submit more than one draft. The truly first version is for your eyes only; your second (or third) attempt is the first draft for anyone else to see.
12. If your instructor requests more than one draft, consider yourself lucky, and even luckier if s/he gives you feedback on the early draft and the opportunity to revise accordingly.
13. Leave enough time to accommodate this recursive process of writing, rethinking, revising, rethinking, revising, rethinking and rewriting. This is the normal way that mature writers write. You are not doing something wrong if you don't get it right on the first try, but you are doing something wrong if you expect to.
14. Proofread carefully for spelling, grammar, citations, and format. If your carelessness undermines your own credibility or annoys your reader/instructor, you have failed to make your argument, no matter how good your research, logic or style.