If I have a tip for anyone, the consulting/startup pairing works wonderfully well....especially if you're in demand. I can turn paid work on and off as needed depending on what we're working on.
I think it's mostly a case of knowing people. Nearly all of my work is from people who already knew me before they needed the work, or knew someone who I had previously done work for.
Referrals and recommendations are worth more than anything else, and people will pay more for someone they know will do a good job. My two current side projects are for an old client of a company I used to work for and had worked with previously (they referred me), and a friend of a friend of my father. Previous work has all been via referrals from friends or clients. Once you do a job for someone, give them a stack of business cards and ask them to refer you to others. If you've looked after them, they'll be more than happy to do it. Since starting my business 3.5 years ago, I've never once had to actually look for work.
I'd strongly avoid looking for work on any website, you end up competing on price, and that's no way to make a living.
If you're up against low price estimates, they're probably using templates, or reusing stuff they've already done for someone else or maybe even outsourcing it overseas. You can't compete with that when you're starting from scratch on your own time. You just have to accept that some people are cheap and won't pay your price. You should never do a job that loses you money just for the sake of winning the job.
Estimation on any project is a matter of breaking it down to the smallest components. Estimate each component with a high/low bracket (i.e. best case and worst case). Find the average, add some slippage (15%-20%) to allow for when you get it totally wrong, or to give you some room if the scope changes (and you want to be nice and not charge more), and you have your number.
Don't ever budge on your hours estimate.
If your client thinks it's too much you can do a % discount on the overall price, but you make sure they're aware that 200hrs is 200hrs. Too many clients think you can somehow build the exact some thing, but in less hours by "trying harder" or waving a magic wand. They'll ask why the guy on craigslist is cheaper, I'd suggest they give the guy a go and find out, and if they're not happy to give you a call back. It may help to ask them if they'd ask their surgeon for a discount :P
But seriously, give up on craigslist. The only people looking there are ones that are trying to save a buck. We've tried a few online "job markets" and found we were estimating $2000 for jobs others were quoting for under $500. A 15 page website in a day?? No thanks!