I think a few people have started out on 'free' sites. My hobby blog is on G blogger but my other blog is on paid host now but started free. I did it that way to 'see' how they measured up and enjoyed my experience so now have a paid site. I don't think a charity on a free site will get much attention or trust. A paid host does give a sense of 'value' to a site and benefit of doubt to the owner.