Here is a video that talks a little bit about it. It talks a little bit about setup and what map to use. It recommends sticks and stones. Other objective based maps will do as well like things like dominations.
For setup he does:
- reflex scope
- lightweight (you can pick something else ghost is also good)
- scavenger (wont work if you kill with explosives)
- dexterity (crossbow aim is slow so its important)
Hopefully you can get some information from this is enough information to get it yourself. If not I hope it at least gives you enough motivation from this to get it lol.