tigerplug: engtech hit the nail on the head that problogging is hard work. However, you're asking the right questions because the work starts with your switch from WP.com. Once you do so, plenty of monetization options become possible and some require your blog to be a certain age -- so the sooner the better.
One such example I've invested in is PayPerPost ( http://www.payperpost.com/ ) that requires a blog age of 3+ months. Multiple PPP bloggers earn $500+ in sponsorships per month for blogging at their own blogs (actually, the current top 10 have earned $585-$790 in just the first half of June) -- plenty to cover the cost of domain/hosting and you select the sponsors, not GOOG.
All that said, focus on quality, selectivity and relevance first, and the earnings will come.
NOTE: Payperpost is not permitted here at wordpress.com. Your blog will be suspended if you use it. So please don't - Mark