I feel that my answear is a little bit basic.
Generally speaking a good person is someone that works for the greater good. That is nice and kind to others, that has a good heart, say and does helpfull things for other people. Someone that doesn't take advantage of anyone and take other people feelings in account so he doesn't hurt them nor does he offend anyone... Someone that helps others even when it's not convenient to him.
Someone that treats everybody with respect wether it's a friend or a stranger...
The list goes on. But you can get the idea.

Well, this is the ideal good person...
The ok good person is someone that summing up their total actions did more good then harm while his worst action haven not been that bad. They did not permanently damage something or didn't do any damage on porpuse or the person regrets the bad things he/she did.

But this is very generalistic... And in my abstract concept there are a lot of ifs, that I could only apply in very concrete scenarios.