1. Your headline's job is to get someone to read the first sentence.
2. The job of the first sentence is to get someone to read the rest of your copy.
3. If you're writing for the net, make sure you have sub headlines, bolded text, links, etc., that are easy for the eye to "scan." Add in catchy subheadlines that will make someone stop scanning and get back to actually reading your copy.
4. User power words: Magical. Unbelievable. Raw. Revealing. Secret. (etc.)
5. Ask rhetorical questions.
6. Be very careful about where you're going to include your calls-for-action. (Also: Don't forget your calls-for-action.)
7. Write for the emotions. Love. Hate. Joy. Anger. Surprise. Anticipation.
8. Outline your features and benefits before writing your copy.
9. Write for your audience. Decide before hand what type of personas will actually be reading your copy.
10. Only write as much as you absolutely have to - no filler.
11. On a related note, (and this is from Stephen King) use this formula: second draft = first draft - 10%
12. Copyedit. Copyedit. Copyedit. Have someone else copyedit, too.
13. Use variance testing to figure out what headlines are working, and what headlines need to go.
14. Tell a compelling story.
15. Tell a compelling story that slowly builds up and reveals a secret.
16. People make decisions based on their want to seek pleasure and avoid pain. Consider this as you write.
17. If you come across an ad or a website with copy that really makes you stop (and want to buy their product) take a moment to consider what's good about it. Copy and paste the copy into a text editor and keep the for future reference.
18. Purchase The Elements of Style right now. (Unless you already own it, in which case: read it again.)
19. Write out as many headlines as it takes. 10. 20. 50. 100. 200. It's that important.
20. Don't "save your best for last." You want to hook the reader as soon as possible, because otherwise they'll stop reading before they ever get to the last parts of your copy.
21. Look at copy for similar products or services. If it's good, what's it doing right? If it's bad, what is it doing wrong?
22. Use numbers. "5 Reasons You Can Save Money Now," "15 Mistakes You MUST Avoid"
23. Speaking of numbers, use bulleted/numbered lists.
24. Assume you're reader has no imagination. It's YOUR job to turn your features into benefits. It's YOUR job to paint a picture and really get them excited to buy your product.
25. Write more. Practice. Now.