Comment in other people's blogs.
Keeping a blog link in your sig is helpful.
Write frequently.
Join a blogging forum or something like that. I like 20somethings.ning.com myself.
Some of it is just luck. Some blogs, like some people, get popularity and hits for no reason I can understand. Also, if your blog is new, people may not visit very much in the beginning, but you'll pick up momentum with time (as long as you write interesting posts frequently).