If people do good to you, pay them back with good. Try your best to always return favour whenever the opportunity presents itself, however you can.
When people mistakenly wrong you, forgive them. When people deliberately wrong you, retake revenge whenever you can, without breaking the law. If you must forgive deliberate evil done to you, it should be because something very good will come out of the forgiveness.
There is a Japanese Legend that says:
"Whether it's a machine, a house, or a relationship. Maintenance is always cheaper than repairing." What you don't maintain, you eventually lose.