You can't have too many tips when it comes to blogging. One good source is an article at NetGuideWeb which is pretty successful at compiling tips from various blog authors into one place. Here's one of my favorites:
"In a personal blog, there needs to be something that sets it apart from others in its class. It might be that it's particularly useful -shares inside-track knowledge, provides up-to-the-second analysis, hard-to-find links. Or it might have a point of view that's unusual, funny, insightful."