Always practice forgiveness whenever U think of a wrong done. Forgive others, and forgive yourself.
Forgive others for your own sake. Assume a man named Zan did U wrong. Forgive Zan. Even if U will never see Zan again, so U think it won't matter, forgive Zan. Also know that if U do see Zan again, forgiveness doesn't mean forgetting. U can intelligently respond to Zan's presence, especially if U've forgiven him, combining hope in his improvement and caution of his past.
If U don't forgive Zan, then each time he comes to mind U will suffer a little. U would add injury to injury if U didn't forgive him. U might even harm yourself more than he harmed U. Sometimes it will feel difficult to forgive, and U will have to forgive over and over and over. Stay patient with yourself and continue to forgive, like all things it will eventually pass.
Sometimes past versions of yourself have done U wrong. Forgive every past version of yourself, for U wouldn't exist without them. Practice Gratitude for the contributions they each made to everything U enjoy about your life now. Due to the path dependence of life U couldn't exist now without each mistake in your past lives. Forgive your past selves and life your present life with the hope that your future selves will forgive U for the mistakes U make now. U won't get everything right, but don't let that stop U from living and from doing the best that U can.
Sometimes even your best intentions can result in harm, so forgive yourself. Sometimes other people's best intentions can cause hurt, so forgive others.