Kicks are the most difficult penalty enforcement. For fouls be Team B it can be previous spot, PSK, or 3 & 1. Hopefully this helps simplify the enforcement for you for Team B fouls during punt plays:
If Team B fouls while trying to block the kick = previous spot
If Team B fouls during the kick or, by philosophy, setting up the return = PSK (if other requirements are met)
If Team B fouls during the return = 3 & 1
If you remember this, you'll get 99% correct.