You must check first the project. You need to study the white paper and the development team. Then check the bounty pool and the budget for each campaign.
Well, I usually check the team more than the bounty because it's not about how much you will receive but on how big the project will achieve.
Just like Populous for example, the bounty is not really that big but the price rise x50 before it fall I guess, so bounty hunters who gold benefit a lot of the success of the project.