Writing Content
Writing content for a blog is similar to writing for a Web site in many ways: reading on a screen is difficult so keep it brief, use headings, sub headings and bullet points. Let people scan easily.
Follow this link to access a PDF of a recent presentation about writing content for a Web site. It does not all apply to blogs, but it could give you some useful tips.
http://blog.saratogauk.com/archives/51
My advice: take the leap of faith. Put content on your blog. We all have to start somewhere and only through trial and experimenting can you improve. Write with emotion, humour, etc - generally, people do not want to read slick marketing copy on a blog.
Good luck
Wayne