It is actually really hard to find out, what bounty is going to succeed and which bounty will not be a success. There is actually no basic rules. But there is some way, you can find out 80% good bounty. The rules are simple. Try to participate with the trustworthy bounty managers campaign. There are many bounty managers who are trustworthy. Besides, there are many new bounty managers as well. So I am now just participating in the bounty of good managers.