√ In preparation for Yom Kippur, we should examine in our memories if we had harmed anyone: a friend, a colleague or a member of our family. During Yom Kippur, by the admission and confession of our sins, the transgressions between us and God (Shabbat, Kashrut, Tefilin, etc.) are effectively forgiven. But we are not forgiven for the offenses made toward another human being (bullying, cheating, lying, embarrassing someone, lashon hara', etc, etc.) unless we ask first for their forgiveness.
√ Asking forgiveness is probably one of the most challenging tasks we might need to do in our lives. Because we need to admit and say: "I WAS WRONG". We can ask forgiveness personally or by phone or if that is not feasible or emotionally possible, by a letter or an email.
√ If the person we have offended does not want to forgive us, one "should take along three men to intercede for him and plead with the offended to forgive him. If necessary, he must repeat and try three times as his penitence. ... If he asks forgiveness three times and the other refuses to forgive, he need not return again..." (Meam Loez). However, if one has offended his father or mother there is no limit to the times he needs to go and seek their forgiveness.
√ In the same way we expect other people (and God!) to forgive us, we need to be easy to forgive and forget. "Before going to sleep at night we should say wholeheartedly: If anyone has injured or offended me in any way, I forgive him or her completely and I bear no hatred toward anyone. One thus fulfills the commandment 'You shall love your neighbor as yourself"
√ We should also settle our personal monetary debts before Yom Kippur. For example, if we have borrowed money from someone and we have not paid it yet. We should also pay or send the payment for our donations before Yom Kippur.