Freelancing with Companies in Other Countries?

DutchSter asks: "I've been doing PHP web development for a few years now, including a few small jobs for a client in the UK (I'm currently in the US). The jobs have been so small I've never worried about a contract or anything. I was recently offered to do some long-term projects (about 6 months of full-time work). Does anyone have experience doing freelance work for another country, and if so, how did you handle contractual issues? Basically, I'm looking to minimize the risk of me being ripped off, and second, eliminate problems caused by miscommunication due to the lack of a written agreement."