John has a strong point about free vs paid hosting.
Free is ok to try for brief time to see if you like it and stay with it. Say maybe a few weeks.
Look at it this way;
In the naming convention of DNS hierarchy you have (we will use
www.someonselsename.com)
Top level name = .com
Second level = someonelsename
Third level = www
You have a real IP address, a location on the web, which is index by the search engines as a top level.
Now look at a free site; will call it (yourblog)
Notice you are not a .com, you are a subdomain and this is your website title;
www.yourblog.someonelsename.com
To the search engines you look like this
.com
someonelsename
www
yourblog (4th level)
Search engines are indexing on the top level domain 'someonelsename' their IP address and not you.
If you have been there long enough to get popluar and now you want to move, guess what... You will start all over again. OUCH!
A client of mine just yesterday said to me "Dave I think I may have to move to a new server. What is going to happen to my Ranking?" Just look at his client list
http://www.cga2k.com/cga_clients.html that he has developed over the years. At the moment I don't have a complete answer to lesson the impact, but it won't be as bad, as if it was like the example above.