If you could give me one piece of advice as I ask someone to forgive me for what I have done, what would that be?
For one and only one piece of advice, I would say this: Once you have asked for forgiveness, please be patient with the person who was hurt. Do not expect instant forgiving from that person. Asking for forgiveness requires a humble approach and letting the other person choose when it is the best time to forgive.
For additional information, see Learning to Forgive Others.