Work going well... too well?

I didn't know if this could be possible, but work seem to be going to well lately, there's more jobs to take on then I have time. Already pushing something like 64 hours work week (it's not as bad as it sounds, I got used to it, never been one for TV or computer games anyway)

The problem is, i never intended to do freelance for this long, I always thought I'd do this for a few months then get me self a proper job, so I could learn more, have some colleagues and generally live life in HK. it's starting to look as if there's no need to get a proper job, I've fairly sure I can support myself with my current workload, most likely better pay then a full time job. I also enjoy the flexible work hours, sleeping til 10 everyday can't be a bad thing. The arguement is that I don't necessarily feel I know enough about the field yet. My ultimate goal is to have my own creative agency and with so much work it's looking as if I'm going toward the right direction, but never really worked inside a creative agency there's only so much i know about the working of one... seems like to dive into it head first is a bit risky, but some of these projects are just too good to pass on. can't say no to the guys I train Parkour with, nor can I say no to a DJ friend/mentor to design a site for a good cause and the latest one is to design for a tattoo artist I admire for a long time.  You see my predicament? there's also 3 other website I had already said Yes to taking on too.....

What should I do? keep on freelancing til I run out of work? or learn to say NO to clients no matter how interesting the project could be?????