1. Join a bounty project promoted by reputable bounty managers here. You can try to search a thread here in the forum for them and there are quite few results of them in a list form.
Reputable bounty managers don't provide any guarantee, the project under their management will success. So don't just trust it, always do research before joining
Maybe you can add no 6
Make sure go to
Scam Accusation board and find the project you want to join there