For me, the gems that I choose are:
1. Managed by famous BM
2. Bounty funds via escrow
3. The bounty allocation is reasonable, not too big and not too small.
Then just do a little research on the project to be followed.
That's an important point, because we have to make sure the bounty is managed by a popular manager and the bounty payment is escrow status. But don't forget to add that each project must be analyzed for potential because some low reputation projects also use the escrow payment method.
The trick is, from that list of three positions, you can only have two. You can join a bounty with a cool manager that escrows funds (for example julerz12), but such bounties have unlimited amount of participants and in the end you get $1-5. Of course the amount might change if the price gets pumped, but no one usually hold bounty rewards for such a long time and prefer to dump them.
Bounty allocation is a tricky thing. Often we see $50-100k in
project tokens. A lot of hunters see $50-100k, while more experience understand that this amount can be anything. Projects can randomly set tokens value, and often that price isnt the same we see during trades. Projects value their tokens much higher than real price. These $50-100k in reality are several thousands only.