Say, "I'm sorry" 
If you do something that you shouldn't don't be afraid to say, "I'm sorry"or write a little card or note expressing that you are sorry. Remember everybody has feelings even if they pretend that they don't. The best apology is changed behaivor. If you are wrong~ own up to what you didn't do right. That is how you learn and earn respect. Sorry is not enough, you actually have to change. Apologizing does not always mean you are wrong or or that another person is right. It just means you value your relationship more than your ego.