I've been blogging regularly for a long time now (I keep a blog on my teaching experiences that a lot of OTers read, its in my sig).
I prefer Wordpress to Blogspot by a lot. Blogspot is slightly easier to use, but WP has a much better stats collection system, more plugins, and has a great tag feature that can help direct people to your site.
Advice for blog writing:
1) Update on a regular basis. If you want people to read your blog, you need to write 2-3 times a week, preferably on regular intervals. I'm not great at doing this, but my traffic plummets when I forget.
2) Comment and read other blogs! Try to leave a handful of comments every day. WP makes it pretty easy to find blogs on similar topics using the tag surfer. This is how you'll build a community around your site, get regular commenters, etc. Twitter is actually really good for this as well.
3) Be specific. The best blogs typically have a strong, coherent theme.
Good luck, and have fun! Blogging has been one of the few good things I've gotten out of my experience here so far.