Pray to God to enlighten you to make a good examination of conscience since your last confession
Make an act of contrition on your sins
Make a firm resolve not to commit further sins
Confess them all without leaving purposely any of them. If you recall some serious sin you forgot to tell, rest assured that it has been forgiven with the others, but be sure to confess it in your next Confession
Perform the penance assigned by the confessor.
After receiving the sacrament of penance make sure to render thanks to the Lord.