But sometimes I find myself rather confused as to what to pray. Some gods demand certain requirements/restrictions to what they want to hear. Some are open. The biggest problem is pray something up, then realizing, 'shit, what did I just do?!'

I found praying to good aligned gods a lot easier then to evil aligned due to one simple fact. Good aligned gods are good and you have little to fear of getting plagued, poisoned, smited for unintentially saying something unappropriate 'for the most part'.

Evil aligned priests 'which I play quite a lot of' I find are harder to think of wordly prayers and instead, I'll try to kill someone and then pray.

Your character is up to you. Only you can decide how to interact. I remember being slightly afraid to IMMteraction, at least until I saw pictures of Nepenthe, Scarabaeus and Shokai on the Custodian. :-P