What i like about cgtrader's freelancing system, is that its very secure and unless you do something very stupid, like start working and/or deliver files without securing prepayment, it's pretty low chances that you'll be screwed here. I did more than 100 jobs here and never had problems with clients. But of course you still have to be careful and think before acting - i had several cases where people tried to convince me to start working on their projects without prepayment and would dissapear when i insisted to follow proper procedure.