I took a workshop where a marketing company talked about using Twitter and Facebook to promote your art. Someone asked whether it was better to use a personal page or a business page, and the marketing woman said it depends on the person. I have seen people use a personal page for promotion instead of making a business page. You can use a personal page like a business page, and put up links, pictures, and whatever other information about your work. You can also use it to reply to messages from fans and put up information about events. If you do hit the limit on number of friends, then you can just put up an announcement about that and create a business page then and tell everyone to become a fan of that.
This doesn’t work as well of course if you like to keep your personal and business lives more separate. A lot of people like to put family pictures up and post about political stuff and other things that wouldn’t work well in between promoting their work. But if you don’t already have a personal page then it could work for you.