From a post over on Robin Good, we have Sharon Housley’s 10 great tips on how to write a successful blog

1. Stay on topic
2. Be informative
3. Old news is not news
4. Adhere to a schedule
5. Clarity and simplicity
6. Keyword-rich
7. Quantity matters
8. Frequency
9. Spell check and proof read
10. RSS

Read more here

I would also add:
11. Include photos
12. Use subheadings, bold etc where relevant
13. Cross-link/trackback
14. Balance quantity with quality
15. Link to your older posts
16. Talk to people via comments

There is so much more, but these are my top tips! Post a comment if you have other important ones you’d like to add.