The Sacrament of Penance (also known as Reconciliation) has three elements: conversion, confession and celebration. In it we find God's unconditional forgiveness, and as a result we are called to forgive others.
Five Steps for a Good Confession
Examine your conscience thoroughly
Be sincerely sorry for your sins
Confess your sins to the best of your ability
Resolve to amend your life
After your confession, do the penance the priest gives you
Procedure in the Confessional The priest may prompt you to begin. You respond: "Bless me Father, for I have sinned. It has been (mention the amount of time since your last confession here) and these are my sins."
Start listing all your mortal sins first and the number of times you have committed these sins.
Then proceed to mention some of your venial sins. When you are finished, say "For these and all the sins of my past life, especially for my sins of __________ I am truly sorry."
The priest may give you some advice, and then will assign your penance and ask you to say an "Act of Contrition". You then wait for his absolution.
After the absolution, thank the priest and go do your penance; preferably before the Blessed Sacrament.