how can I choose the best bounty
I think for a very good bounty
You need to check up the bounty rewards, amount of allowed participants, the limitations, terms and how long it takes for the whole of the campaign too
Naturally, instinct will tell you a good bounty
If a bounty says 10% of tokens sold during ico; you can be wary and more careful too
This bounty campaign has helped this world in much better way because of the reason that it has reduced the rate of unemployment to a very significant figure and that it has helped so many people in having some good earning for a better living. You just need to learn the things which you need to know and that you need to look for such campaign which can help you in better earning.