By all means make rules for yourself that you think are fair and honest and stick to them.

Being upright, honest, & forthright is a good thing in this world and people will tend to respect you for it.

NEVER EVER assume or expect everyone else to following these exact same rules -even should be. Everyone has their own ideas of the "correct" way to do things. Assume no rules at all except for those written down and signed in front of a notary. Even then, have a lawyer on speed-dial if you expect them to be followed to the letter.