Well, one approach is to team up with a consultant/contractor in the US. Preferably someone you know personally that will not skim off too much. This reduces the risk for the clients, as they have a US party as the legal contractor, don't have to do international payments, etc.

Of course, usually that kind of business is started by the guy in the place with the clients. It doesn't have to be huge body shop, in fact the smaller, the better they have to treat you. My previous company used such a contractor (notionext.com). I don't know how easy it is to leverage yourself into having direct clients; probably quite hard.