Business apology letters should be typed on a computer. Use a serif font, such as Times Roman. Once you have typed the letter, print it on good quality, white paper.
Clearly state the problem and offer your apology right in the beginning of the letter. Give some explanation for what happened and then clearly state what actions you are taking to solve the problem or improve the situation.
Put your signature. Ideally you should hand-sign the apology letter with a black pen.
When to send an apology letter?
Well, say sorry as soon as you realize that you have committed something wrong or inappropriate. By sending an apology letter before it gets too late, you will be able to save your friendships and business relationships.
How to Write a Personal Apology Letter?
Personal apology letters should be written on a piece of paper. Offer your apology in the beginning of the letter. Clearly state what you did wrong and accept responsibility. Note that in an apology letter you are not supposed to blame the other person. Express sincere regret in your apology letter and promise not to repeat the offensive action. You may even express your desire to meet the other person at a restaurant or some other place so that you can apologize in person.