The process of forgiving and being forgiven is very powerful and it should be taken quite seriously, especially if you have been hurt by others or you yourself have hurt others. Everyone deserves to be foregiven if they are truly sorry, but by simply saying you are truly sorry doesn't cut it, you truly have to feel the pain you caused to another soul in order to be forgiven (this is my opinion only). Firstly, you must admit your mistakes and are truly repenting for your past misdeeds and if possible go to the people to whom you committed wrong, and fall at their feet and beg for forgiveness. If they forgive you, then you have done your 'prayascitta' or atonement for your sins.
If this is not possible to directly meet them, then at least write to them, begging for forgiveness. Krsna will hear you.
If this is not possible, if those people have passed or you don't know where to locate them, or there may be other practical problems, that you cannot get in touch with them, then you should ask for their forgiveness mentally and pray to Lord Krsna to forgive your sins.
After doing this, take up to the process of bhakti-yoga to Lord Krsna. Depending on one's sincerity, bhakti will remove all the sins eventually Lord Krsna gives you this guarantee in Bhagavad-Gita 18.66:
"sarva dharman parityajya mam ekam saranam vraja, aham tvam sarva papebhyo moksayisyami ma sucah - Abandon all varieties of religion and just surrender unto me and I shall deliver you from all SINFUL reactions. Do not fear."
"Hare Krsna Hare Krsna; Krsna Krsna Hare Hare; Hare Rama Hare Rama; Rama Rama Hare Hare".
Lord Krsna will hear your prayers, and engage you in His service, and He will remove all our sins in the course of time.
Here is a quotation from Srimad Bhagavatam 6.2.13 (6th Canto, 2nd Chapter, 13th verse):
"One who has killed a brahmana, one who has killed a cow or one who has killed his father, mother or guru (spiritual master) can be immediately freed from all sinful reactions simply by chanting the Holy Name of Lord Krsna or Narayana. Other sinful persons, such as dog-eaters and candalas, who are less than sudras, can also be freed in this way".
Also Srimad Bhagavatam 6.2.9-10:
"The chanting of the Holy Name Lord Krsna is the best process of atonement (prayascitta) for a thief of gold or other valuables, for a drunkard, for one who betrays a friend or relative, for one who kills a brahmana, or for one who indulges in sex with the wife of his guru or other superior. It is also the best method of atonement for one who murders women, the king or his father, for one who slaughters cows, and for all other sinful men. Simply by chanting the Holy Name of Krsna, such sinful persons may attract the attention of the Supreme Lord, who therefore considers, "because this man has chanted My Holy Name, My duty is to give him protection."
You should not chant the Holy Names and continue to do sins thinking that the chanting will cleanse all the sins. That does cut it. You must admit one's mistakes, sincerely from the heart repent for one's mistakes, and
every day chant the Holy Names, which will give strength and realization from committing any further sins.