1. Make it genuine - Anyone can spot a false apology and it will do more harm than good. A genuine apology is aimed solely at taking responsibility and overcoming a disturbance. There are no hidden obligations or expectations attached.
2.Don’t justify your actions - If you are busy explaining why you did what you did, it will start to sound like you aren’t apologizing at all, that you aren’t ready to take responsibility. A brief explanation may help understanding, while a justification may just fuel the disturbance.
3.Make a commitment to change - If you can’t confirm that you mean to improve, then you aren’t committed to an apology. If you aren’t committed to changing your habit of getting home late, don’t say “Sorry I am home late”. This will be a hollow and ineffective apology. You are better off thanking the other person, “Thanks for putting up with me coming home so late. I appreciate it” and taking it from there.
4.Phrased you apology carefully - Make sure the other person knows why you are apologizing. “I was passing by so I thought I’d drop in and say sorry” is a lot different to “I wanted to come and apologize because I really do care about this relationship”. Don’t fake it. If you have a good reason to keep the relationship alive the other person will want to hear it.
5.Be prepared for an awkward conclusion - While sometimes an apology is followed straight away by a counter apology and peace and flowers and little birds carrying banners of love through the air, not everyone reacts this way. Some people will behave indifferently, some will behave coldly, and some will react in a downright hostile way. This is out of your control. You have made the step to apologize. Doing it in a productive way is the best you can do. Maybe the other person will appreciate it now, later, or never. No matter what, you have done your bit and you can relax. The rest is up to them.