u need to be careful

Get a through investigation of the potential marriage partner. You might need to pay some fee on county municipals to look up records.

Besides, try to make sure you can control her/him as well as possible for three years. Don't look at the money. That money is nothing compared to security and GC.

After get you formal GC, you are safe. And make a safe divorce at the right time.

And before you go to marry the person, make sure you do not have other choices. I don't suggest people take this way unless all other doors are closed.