I did the freelance/startup combination for about five years. Its ok once if you can pull it off, but I do not recommend repeating it. I have a lot of friends that do this, and on the whole I think it is a vicious cycle. I don't mean you shouldn't freelance to fund a company. If that seems the way forward, then do it - once. But you shouldn't do this repeatedly. Its an easy cycle to get into. Instead, you should work at startups in between founding startups.
I find that you can get into this pattern:
1) Focus on billing in boring contract work to get spare cycles to work on startup. Learn new skills to apply in new startup on your own time. 2) Startup makes progress, focus on startup, startup doesn't make it (most don't), savings run out. 3) Cling to hope. Debt. 4) Repeat.
Most people I've known do not eject efficiently in stage 3, and bear excessive credit card debt, etc. Whereas if you get a job at a startup, you can enter this pattern, and even if all these companies tank, you're better off:
1) Work a job at a startup where you do very interesting work, get paid to refine your skills, gain highly relevant experience. 2) Repeat 1, increasing in job coolness/responsibility. Save money. 3) Now that you've built a reputation and network of excellence by working at startups, start a company that has a better chance of succeeding using your experience, cutting edge skills, network of potential co-founders and relationships with investors, potential employees and customers.
I was in the first pattern, now I'm going for the second. Looking across many successful founders, this seems to be the most frequent way to arrive at a good outcome. I value the experience from the first pattern, but my life is so much better now that I'm in the second. I wish I'd entered it earlier. Note: I had to move to silicon valley to enter the second pattern.
You might do well with your first company part timing it, but I find that struggling and part timing it is just a less effective way to learn to build companies than participating in a later stage company. Other than the entrepreneurial drive itself, I think that building companies is actually something you learn, and that its something best learned by doing. You can get early stage experience just starting something. You only get that later stage experience in your own company if it makes it that far - but you can get it by joining a startup at any time.
I think a lot of people, especially those outside of silicon valley, miss this completely. We tend to focus on the icons of silicon valley - pairs of young people that hit it big the first time out. But most successful companies actually come from experienced engineers/entrepreneurs that got on the job training at other startups. People work together, then they start companies together. Ever since the Fairchild traitorous 8. http://en.wikipedia.org/wiki/Traitorous_Eight