You can blog about work-related things (discussions you have with clients are always great thought-starters, although because my clients sometimes read my blog, I never use their real names or even real examples without protecting their names and organisation).
You can blog about cooking or fishing or breeds of cat. I have a blog on
- manhole covers photographed in my travels
- day-by-day account of training programs I've been in
- the improvised show I produce.
I also keep a private blog I keep to remember things I want to blog about!
You can use blogspot (just click up on the Create Blog link on the top RHS of this page). You can use wordpress. You can probably use a ton of others, but don't let choosing one stop you - the sooner you start, the sooner you'll have something.
Of course like anything, numbers don't mean much. If your clients read your blog, then you're ahead!

