A big Tikun for any sin is to confess that sin in front of G-D.
Besides the standard Viduy prayer one should verbally confess the sin in as much detail as possible. As he talks he should realize what he had done and regret it.

King Dovid said "As long as I was quite and did not verbally confess my sins, my bones decayed as I groaned in pain all day long. Day and night you (G-D) heavily laid your hand on me, my energy became withered like the dryness of the summer. Therefore I confessed my sins to you and I did not try to cover up my bad deeds, I said I will confess my rebellious acts to G-D, and you therefore forgave me for my sins." (Tehilim 32)

Lock yourself in a room and start confessing your sins.
A better place to do it is by a grave of a Holy person, go to Rebbe Shimon bar Yochi.
There are people who stand by Rebbe Nachmans grave in Umon for hours confessing all their sins.
Note, just like there is Lashon Hara (gossip) about other people, it is also forbidden to talk bad about yourself. When you confess do it in a way that it will not be heard by other people.