I will focus on Christianity since I know most about it.
Do not try to extort money from members by charging exorbitant amounts of money for religious services.
Opinions differ on tithing, but we also have examples of monetary payment for sins.
Do not claim to have supernatural effects on reality.
People often pray for people to be healed and they will be healed. That is clearly belief in supernatural influence on reality.
Do not believe that all members of Other Religion X are doomed to damnation.
Are you kidding? It is even worse than believing they are doomed, but that you must go and punish (kill) them yourself. See Deuteronomy 8-19, 13-6, 13-12, Jeremiah 1-16, and 16-10. And this nearly pales in comparison to Islam.
I am afraid many more religions offer this bunk than you seem to believe.
Never test for an error condition you don't know how to handle. -- Steinbach