Ensure that you’re being an ethical and conscientious biller. Not only will it help you get paid, it will help build your relationship with your clients.
Hang out on the internet long enough, and you’ll run into some pretty rude people. It’s inevitable, but what really matters is how you deal with it. Feed the trolls at your peril.
Clients from Hell is a fun site, but sometimes I worry that it will give design and development professionals a bad rap.