Dan Frommer is a technology writer but his blogging tips are easily applied to edubloggers also. This is my favorite:
Write the site that you want to read. That covers story selection, length, frequency, style, vocabulary, attitude, humor, level of sensationalism, and more. Don’t publish anything you’re not proud of. Be yourself.
A participant in my session at CMC-North asked me how to develop a community through blogging. I told him I saw a lot of bloggers come online, post a few times, get depressed they weren't getting the traction they wanted, and then wander off. I said you had to do it because you were satisfied by the act of writing itself, because you were looking forward to one day reading about the teacher you used to be.
I also said that I follow nearly every link and comment back to the blog that sent it. Often times I'll subscribe and, because I'm totally lazy, I rarely unsubscribe. So draw in comments and reciprocal links by linking and commenting generously. But only after you're writing and sharing because you find it inherently satisfying.
BTW. Given the choice, Daniel Schneider chooses blogs and Twitter over the formal professional development of math conferences. Conference organizers take note, get nervous.