Blogging in a free blog hosting provider is an option for you who have no budget to buy your own domain and a hosting space. I had my blog runs in a free blog server and now it has Pagerank of 4. As you know that you can monetize your pageranked blog by selling links or for paid review.s I lost that opportunity because of the TOS (term of service) of the provider states that I can not monetize my blog if using their free service.
If you have a vision about your blog as well as its future, you should consider about having your own domain name and hosting space. Domain name and hosting space are cheap now so you do not need a lot of money just to start your own blog. The next question is where to buy domain and hosting.