You must first understand what you did wrong in order to change it.  Define the mistake. Did you say something wrong? Did you accidentally make a mistake on a project at work or at school? Did you forget to clean the bathroom like you promised? Understand how and why you made the mistake. Did you do it on purpose and then later regret it? Were you simply not paying enough attention? Think to yourself something like, "How did I forget to clean the bathroom? Did I not want to clean it and avoid it? Did I get too busy?" If you are not sure what you did wrong, ask someone (friend, family member, teacher, co-worker, boss) to help you find out. For example, if someone is upset at you, you can ask,"I sense that you are upset with me, can you explain?" This person may then say, "I'm upset with you because you said you would clean the bathroom and you didn't do it." Look at your patterns of behavior and how you have had similar issues in the past. Are there other times when you forgot to do something? Write down any patterns or themes you notice that keep coming up for you. This may help you identify a larger goal that you need to work on (attention span, certain skills, etc). For example, perhaps you tend to forget tasks that you don't want to do such as cleaning. This could indicate you are avoiding the task or that you need to become more organized in order to remember to complete certain responsibilities. Understand that your mistake is your own. Take the responsibility that is yours and avoid blaming it on someone else. If you play the blame-game then you cannot learn from your faults, and you may continue making the same mistakes over and over again.  Write down the parts of the problem that you contributed to, or the specific mistake you made. Identify things you might have done differently to produce a better outcome.

TL;DR in Indonesian:
Ketahui kesalahan Anda. Ingatlah kesalahan Anda di masa lalu. Ambillah tanggung jawab.