I have twenty or thirty notebooks and journals filled up with snippets about writing, my plans for stories, bits of dialogue, interesting ideas, plotlines, scraps of short stories, and a dozen other things. I carry one with me at all times and it takes me a couple of months to fill one up.
One of the things I've kept in one of my notebooks was a collection of writing tips and rules that I've collected over the years in my travels. From teachers, from books, from wherever. Most of my career has been spent screenwriting, so a lot of these are most applicable to that, but I wanted to present them so they might be of use to you as well.
I've never stopped collecting these over the years and I never will.
To start the list are Kurt Vonnegut's eight rules of writing. They are the first in my notebook and, I think, the most useful. I'll add a star to those I think are applicable most to screenwriting. Some of these aren't applicable to everyone in every situation, but for the most part they're all helpful.
NOTE: I've been writing a series of posts elaborating on each of these points. Just click on the number to be magically transported to the post that elaborates on that particular bit of advice.
UPDATE (August 2013): I've added a few more I've collected and have done a bit of renumbering at the bottom.
1) Use the time of a total stranger in such a way that he or she will not feel the time was wasted.
2) Give the reader at least one character they can root for.
3) Every character should want something, even if it's just a glass of water.
4) Every sentence should do one of two things -- reveal character or advance the action.
5) Start as close to the end as possible.
6) Be a sadist. No matter how sweet and innocent your leading characters, make awful things happen to them--in order that the reader may see what they are made of.
7) Write to please just one person. If you open the window and make love to the world, so to speak, your story will get pneumonia.
8) Give your readers as much information as possible. To heck with suspense. Readers should have such a complete understanding of what is going on, where and why, that they could finish the story themselves should cockroaches eat the last few pages.
* 9) No one likes to read large blocks of text, keep action to one or two lines but no more than four.
* 10) Unless you're directing, keep inflections, camera direction, and editing suggestions out of the script.
* 11) Action should be clear and concise, like a children's book.
12) Be economical with your words. Omit all words that aren't 100% necessary to tell the story.
13) Statements like "begins to" and "starts to" are nonsense. Someone does something or they don't. It's just more words for people to read for no reason.
14) The more sparing you are with adjectives and adverbs, the more impact they will have when you do use them.
15) Monologues are for the theatre. Break up long stretches of dialogue with actions, reactions, sense of place, other senses, etc.
* 16) Be as conscious of how the page looks as you are of what it says. If a page looks easy to read with little text, readers are more likely to read it.
17) People talk in contractions and broken sentences. Virtually no one speaks perfect English. (See Twain's dialogue.)
18) Be true to your characters and your story. Let them write the text.
19) Care deeply about each word and line. Details down to every word mean something, own them and care about them.
20) Read other peoples books and screenplays that you admire and are better than your skill level. You don't necessarily need to switch to their style, but adapts their strengths into your style and learn from their mistakes.
* 21) Avoid metaphors and similes in the action. Readers generally skim and if they only skim the metaphor part of the sentence, they'll get images in their head that aren't actually in the movie.
22) If someone doesn't understand the images you're trying to show them, if someone doesn't "get it," it's your fault. As a writer, it's your job to make people "get it" and if they don't, you haven't done your job properly.
23) Avoid cliches. Avoid them in characters, action, dialogue, story, plot, and anything else that risks being cliched. If you must use a cliche, add uniqueness and freshness to it.
24) Don't write a story you only have half a heart for. It does a disservice to you and a disservice to the material.
25) It's a good writer who can write what he knows, it takes a great writer to write what he doesn't. Cut your teeth on what you do know and research the hell out of everything you don't and you'll do fine.
26) Never show people your rough draft. Show people your fifth draft and tell them it's your rough draft.
27) There is no such thing as a final draft.
28) Don't ask people to read your material for praise. Tell them to hate it and criticize it to no end. If they do that, you know exactly what to work on.
29) Don't get defensive or mad when someone criticizes your work. Criticism is done to help, not hurt or compete. And chances are the more mad they make you, the more right they are.
30) Don't go back and revise until you've finished. Otherwise you won't get past page 15.
31) The hardest part of writing is starting. Finishing is no trick as you've already committed to start.
32) Qui-Gon Jinn said of pod-racing, "Feel, don't think. Use your instincts." The same is true of first drafts.
33) 32 is only true if you have an outline and a roadmap. Otherwise it's just meandering drivel.
34) It's helpful to write scenes to music of a similar tone. It will give your scene a beat and pace you don't have to think about.
35) Qui-Gon Jinn said, "There's always a bigger fish." You will never be the best writer. There's always someone better. Learn from them.
36) George Lucas told Irvin Kershner, "Don't expect things to work." That hold true of writing and filmmaking in every aspect, starting with the first words you put down on the page.
37) Fairy tales and kids stories should have frightening things in them.
38) The ego is the enemy of the writer. Listen to what others have to say about your material, even if you don't agree with them. Don't assume you know better than they do.
39) Have fun.
40) Wait a while before you think you're finished with something. After a time away from the material you'll see problems you hadn't seen before.
* 41) Try to avoid, where possible, the thoughts and feelings of characters in the scene setups and action. It won't play visually.
42) Don't guess trends. Write what you want to read or see.
43) Paranoia about theft is wasted energy.
44) Know your mythology. Know your classic story structure. Know your Robert McKee, know your Joseph Campbell.
45) Irvin Kershner said, "A director is always guessing." So is a writer.
46) Read your dialogue out loud to yourself to make sure it's natural. That's what Tennessee Williams did and look at how that turned out.
47) If it helps, write parts for dead actors you admire, then rewrite them in your revision for living actors. It gives you two different perspectives on the character and adds an extra, easy layer of depth.
48) Story isn't alchemy and inspiration. It's a craft, like engineering or mechanics. There are parts to everything and nothing extra. Learn your trade with this in mind.
49) Learn to do everything you can in the world of writing on your own. If you don't believe in your work enough to bleed for it in every way possible, why should someone else?
50) Pay attention to the geography in your prose. People, places, things, everything. It's important.
51) Pay attention to whose perspective you're writing from and why
52) Get visceral in your descriptions, particularly as being experienced by your POV character.
53) Don't be afraid to tear the guts out of a story. I know you feel like you wrote what you wanted to the first time, but you're probably wrong.
54) Never stop learning. Never stop studying. Never stop reading great books and excellent films.
55) There are no rules to writing. Only principles, guidelines and suggestions. Take each of them with a grain of salt.
56) Reading tips about writing won't make you a better writer as much as more writing will, but that's not to say they aren't helpful.
(While you're thinking about it, feel free to check out my books Lost at the Con, Operation: Montauk, and Man Against the Future.)