One thing you need to do is check the roadmap of the tokens that you have and see when will they list them on exchanges. Usually they will also mention which exchange they will list it. But either way, you can always check coinmarketcap.com, or for most of the etherium tokens etherdelta.
I personally, after joining a bounty keep track of their project dates like ICO start-end, exhange list on my calendar. Not all bounty's prove worthy at the end, have a dozen of tokens sitting on my wallet which probably wont ever be listed on exchanges.