Some people will lie, cheat and steal if they think they can get a few bucks out of you. Unfortunately, the really smart ones find ways to do this legally.
Other people will stop you on the street if they see something fall out of your pocket that looks like it has the Visa logo on it, and make sure you get it back. If they find a wallet with cash and credit cards in it at a busy airport, they dig through it, find a business card, and call someone who might know who the Jane Johnson is whose name is on the credit cards. A week later, you get your wallet back, with everything intact.
The best way to do business is to talk to new people you meet like they belong in the “trustworthy” category, and write agreements that assume they might actually be in the other one.
Never do work for anyone unless you are either okay with doing it for free, or you have an agreement.
To repeat: NEVER do work for ANYONE unless you are either okay with doing it for free, or you have an agreement.