If you don't have a large variety of jobs to pick and choose from, you're not doing it right.
I'm going to rant here a moment...
The secret to getting more work than you can handle (and charging $100/hr, which is not difficult)... DONT SUCK.
I swear to god, 95% of people out there suck, your competition.
Send emails to your phone, and answer them right away when you're out and about, even on weekends or when you're out having a drink. If you're busy, just say you got their email and will get back to them when youre in the office. Try to answer The amount of replies I hear that say "wow you are so responsive and get back so fast, I love it" is a lot more than you would expect. These are my repeat clients. These are your people and you should take care of them.
It's SO easy too, and so many people wait days to reply. That doesn't mean you need to always be working either, or that you need to suddenly be at the mercy of your email, it just means be responsive to inquiries. VERY responsive.
As far as working, dont leave loose ends. This usually means fixing up those little nagging issues that they probably won't notice. Leave them with something stellar, and go the extra mile even if it means only 5 minutes of work extra fixing something they never asked you to fix or paid you for. It takes 5 minutes, and makes a tremendous impression on them.
I'm making this statistic up, but based on what I see it's gotta be over 90% of people don't do just a few simple things. They take a while to reply, deliver sub-par product, don't communicate well... it has nothing to do with their actual site or product they're delivering, just how they handle themselves, then they whine about not having work. (flurpitude, I'm not referring to you as whining, just people in general).
PS: it seems counter intuitive (I'm going to get a lot MORE bs work and bs replies), but it actually seems to eliminate them entirely. People respect your time and your skill, and they dont' waste your time with stupid questions or emails. They're also willing to pay top dollar for your services without giving you a hard time or anything.