1. Use your real name. Some people blog anonymously, but if you want your blog to play a role in your career or job search, then you'll need to get the credit for what you're doing! So you want to have your name attached to your work.
2. Remember that you're using your own name and watch what you say. You must be willing to stand behind everything you write. Ask yourself how a potential hiring manager would judge your blog ... or how your current employer would feel if something you wrote ended up in a major newspaper with your name attached to it.
3. Post regularly. In order to attract returning readers, you'll need to post a minimum of once or twice a week, and more is better, as long as you're posting quality items.
4. Observe the cardinal rule of blogging: Be interesting! If what you're writing is interesting, useful, or entertaining (or, best of all, all three), readers will find you. If it's not, it doesn't matter how much work you put into your blog--your readers will drift away.