Sorry can people blessed with the gift of ultimate knowledge teach us how to use commendations and what to expect from a mentor?

I don't want to misuse commendations and give them to a helpful and friendly player when I should give them to someone solely because he plays a certain race or has a nice glamour.
Same for mentors if I ever become one I'd like to know if I should be helpful, patient and try to teach others or if I'm just here to fill a spot in a party and being useless.