1. Seek out forks of the app that I use and try them out.
2. Check to make sure there aren't any bugs introduced in the fork.
3. Check to make sure the author didn't introduce a subtle backdoor into the system allowing them to e.g. mint infinite tokens.
4. Check how many tokens the developer minted themselves as the reward for this work, to make sure it's not too many. (Do I actually care?)
Hope the majority of users are paying this much attention!