Just do some research about the campaign that you're gonna participate and check everything about them that makes them legit and safe to join.
Not just some research, you need to find out the prospects of the project, its product, team and an idea of where their ieo will take place or possible exchange listing.
Mere looking at a project, and interaction with the team either chats or ama, you should be able to define what kind of exchange they are able to attract. Dyor always and join Bounties with the aim to get paid big