Add lots of friends: Every time you do a new entry it gives them a reminder that you have a new one up! And if you do a blog daily and you have 30-40 friends, well, you do the math.
Blog about things people will actually read up on: Radical opinions and shameless blanket statements help, Believe me, I know.
Post n00ds: Oh, wait, you're not 18, don't do that.