To me, it's being as good a friend as they want you to. The old " Do Unto Others " rule.
Be respectful....truthful....all the things you want for yourself
What Rifle and Annie said, and what my late husband used to practice - treat others the way you would want them to treat you: with respect, consideration, and honesty.
To me, "Doing Right by a Person" means that you have the other person's best interest in mind as well as your own. You're not going to date someone just for what you can get off of them whether that be sex, dinners, gifts, trips, money, whatever. I guess it does all boil down to treating others the way we ourselves would like to be treated. Isn't that also called The Golden Rule?
Just like everyone has said....yes the Golden Rule...do unto others....
I use the "Three Fold Rule". Whatever you put out (emanate) whether good or bad you get back three times. You have to remember that means that you should temper your actions and your words, which is hard to do sometimes.
Do unto others & KARMA... I agree with Annie & Rifle...