To effect Teshuva with another person, one must ask that person for forgiveness & also right the wrong (e.g. return money that was stolen). Otherwise, it is a hollow gesture. For sins committed against Hashem & the commandments (rabbinic & Biblical) there is a 3-part process. Step 1 is confessing the sin (vidui); many of the prayers in Elul & Tishrei (e.g. Selichot, Avinu Malkeinu, Ashamnu, Al Chet, etc) express this. Step 2 is expressing regret for having sinned (charata). This is an informal, internal admission that what we did was wrong & was detrimental to our spiritual & physical well-being. Step 3 is a firm determination that when the opportunity arises in the future to commit that same sin, we will refrain from doing it (azivat ha-chet). This indicates that our petition for repentance was sincere & was not just "lip service." It may actually take some time until this last condition is met, but invariably G-d will cause us "to return to the scene of the crime" & test our pledge.