1. Choose your domain name wisely - By this I mean a domain name which will give you a head start in generating internet traffic and visitors.
You can use Google's free keyword tool to find keyword phrases which have significant search volume monthly. By buying a good effective domain name you are guaranteeing a certain amount of visitors and page views simply through your domain name being relevant to the searcher's request through the Google search engine.
2. Use WordPress - And I mean WordPress.org which will allow you to have your blog hosted on your hosting company's servers. If you don't, and choose to have your blog on Blogger.com or WordPress.com, you run the risk of losing your intellectual property (your blog) and all your hard work because your blog is not really your own property as you are not paying for your own hositng.
I use, and recommend, Hostgator.com.
3. Fantastico - make sure that whatever hosting you are using that it has Fanstastico which allows you to install Wordpress in about 3 minutes flat with the minimum of fuss.
4. Experiment - a very useful thing to do is to mess about with your WordPress dashboard and familiarise yourself with the various features which makes it so powerful and simple to use.
Experiment with creating posts, pages and using the widgets and you can delete your work when you decide to publish for real.
5. Plugins - a plugin is simply a piece of software which you can install in a flash which allows you to broadcast and ping your site(ie let Google,Yahoo and Ask know each time you post new content or edit old), create sitemaps, add AdSense from Google and many other useful tasks which you will need to do to promote your blog.