I had a new masseur reach out to me through rentmen and suggest exactly this. He invited me over for a free introductory massage, and then we talked shop. He didn't ask for me to write a review afterwards, but I did so to support his business. He had also priced himself a bit below market to encourage new business.
However, not every guy will accept this kind of trade, and might think it's a ploy for free sex. When I first started escorting, I saved up my $ and hired an escort to see how it was done (plus I wanted to meet him... the hot and hunky Peter Raeg). I had a great time and learned from him too on how to conduct business.
But as others have said, I think the biggest danger is your student visa. You do not want to mess that up. If you're deported for working without authorization, you may be blocked from re-entering the US for many years. When I was in London last year I met a masseur who had flown to LA, was determined to be an escort/masseur likely to try to work in the US, and was sent back on a return flight without ever leaving the airport. He's now blocked from visiting the US for five years.