First, when you forgive yourself, you are both the offended one and the offender. And we rarely offend ourselves in isolation. Thus, you should go and make amends with those who also were offended by your actions. This includes asking for forgiveness, changing your behavior and making recompense where this is reasonable.
After that, as you turn your attention to forgiving yourself please keep this in mind—What you have been offering to others in forgiving them (gentleness, kindness, patience, respect, and moral love), you can and should offer to yourself.