essouira,
"Be careful to get a visa if you want to work in the states. Your US employer can't usually get one for you as a flying instructor so you will have to be recruited to a job which needs you to have some sort of higher educational qualification (of course it goes without saying that the job would need you to have a flying instructor rating too - eg marketing director of a CAA approved flying school!)"
Actually there is a way around that problem. Most schools will enroll you in their ATP program (as long as the instructor has less than 1500hrs) on a M-1 or maybe even a J-1 visa, and you can build hrs. This is not really considered 'work' but rather gaining experience towards and ATP license and the pay will be very low.