As part of the newbie blogger initiative all of the sponsor bloggers are writing posts this month with advice about blogging. Definitely check the forum for links to a lot of helpful people.
My biggest tip for you is to just start writing. Starting to type is the hardest part of blogging. The empty page is more intimidating than most people think. The sooner I can get a sentence written out the better off I am. If you can take a first pass at your post and get everything down on the page you're in a really good position. It doesn't have to be gold, it just has to be on the page.
Which leads me to the fact that you can, and should, revise what you write. When I first started blogging I wouldn't always re-read or revise after I had gotten words on the page. That was a mistake. Now, I make sure to do at least one revision pass on everything I write. Sometimes I barely change anything, but other times it makes a world of difference.
Once it's all down on the page and you've done at least one revision pass then it may be time to post. Some posts you'll want to let simmer in the back of your brain while you tweak them over the course of a week or two and that's fine. But for the most part it's better to post it for the world to see. Don't agonize for weeks over whether to post or not. Get your thoughts out there and get the discussion going. You can always write a follow up post later.
Finally, write for you. People may read your blog, or they may not. If you are writing for yourself then you'll always be proud of your posts and it will feel good to get the thoughts out there. You won't overanalyze page views or try to maximize your traffic generation. You'll be writing about what you're interested in and you'll have a better following because of it.
In my mind, the best example of this is my friend and fellow blogger Professor Beej. He writes about games, movies, tv, writing, reading, academics, pop culture, and random thoughts. His blog isn't constrained to a particular niche, but he has a loyal following because he writes about the things that interest him. Don't be afraid to do the same. Write what you want to. After all, it's your blog.