If you know what your sin is, and you feel guilty, thank God for it. This is God's way of helping you to see the need for change in your life. The good news is that you can be forgiven by God. Jesus has already paid the price for your sins.

God has made a provision for us to receive forgiveness of our sins. 1 John 1:9 says, "If we confess our sins, He is faithful and just to forgive our sins, and cleanse us from all unrighteousness."

The first things to do is tell God out loud what it is you did that you know was wrong. Be specific. God is not shockable. He already knows. But He wants you to tell Him so that a right relationship with God can be restored.

Do not delay confessing to God when you know you have sin in your life. Do not wait until you get into church or some spiritual environment. Confess it immediately to God.

If you know when you confess that you fully intend to do the same sin again, then it is quite possible that you are not truly born again. You need to forsake yourself and truly give yourself to Christ. Check out this lesson on salvation and this lesson on repentance.

If your sin was against someone else you will need to ask God to lead you as far as confession and restitution towards that person should be done. The sooner you do all you can in your power to confess your sin against that person to them the sooner you will remove Satan's possibilities for accusing you and bringing you down.

If you sincerely desire to be in a right state with God, and have confessed your sin to God, then believe God's promise that you are forgiven! If you still feel vaguely guilty but you are not sure why, remember that God says, "There is therefore now no condemnation to those who are in Christ Jesus, who walk not after the flesh but after the spirit." (Romans 8:1). Rebuke the evil spirit of condemnation that attacks you in Jesus' name. Keep drawing near to God so that He can shine more light into your heart, so that you can make further adjustments where necessary. But go to God with an attitude that you are already accpeted and loved by Him.

God has forgiven you and forgotten your sin. But you have not, and neither have the demons who saw you. You need to be humble enough to forgive yourself also (who are you not to if God has), and remember that your sins are forgiven and washed away. Satan may bring up old charges but he has no legal right to do so if you have confessed and forsaken those sins.

"As far as the east is from the west, so far has he removed our transgressions from us." (Psalm 103:12) 

If you had a bad relationship with somebody it is best to follow these steps:

Usually there are faults on both sides in any relationship problem. One of the keys to being blessed by God in this area is humility. You may consider that the other person is 90% to blame, while your blame is only 10%. Nevertheless, you are not responsible for that person's attitudes and actions, only your own. There is the possibility you have misunderstood what they said and did. The more you humble yourself in this process the more you can expect God's blessing.

a. Ask the Holy Spirit to help you and lead you to a proper resolution of the problem.

b. The key to your emotional healing is forgiveness. Tell God that you forgive that person, whether they change or not. (Luke 23:34; Matthew 6:14,15; Mark 11:25; Matthew 18:35; Colossians 3:13). Keep on forgiving them as often as is necessary.

c. Ask God to show you where you needed to behave or respond differently in the relationship. Ask God to show you where your attitude is or was wrong.

d. Contact that person - ideally in person, but if time does not permit, by phone and/or by letter. If you have lost touch and still don't feel right about things, ask someone who might know the contact details of that person. Follow through diligently. (Matthew 5:23, 24).

e. Tell them that you are sorry for the way you acted in the relationship. Confess to them all the things you believe were not right on your part. Ask for forgiveness.

f. If you stole things from them, ask them what they would like from you as far as restoring those things and do what you can in the future to pay them what you owe them.

g. Give them an opportunity to confess their faults. If they don't, try to explain how their words and actions made you feel, and the way it seemed to you.

h. If they apologize, express your forgiveness to them. If they don't apologize, then be gracious towards them and express the fact that you are sorry that there cannot be more reconciliation at that time.

i. If hurt still comes up in your mind after the meeting, pray for them and bless them. Ask that God will get through to them with His love and that they will be set free from all evil. Keep choosing a decision and attitude of forgiveness.

j. If they are a believer, or especially if they are a church member with you, follow the steps mentioned in Matthew 18:15-18. Do not bypass any of these steps, or you yourself will enter into sin and get into unrighteous judgment.

You have to be led by the Spirit in these matters. If your sin has not hurt that person, it is best not to say anything. For example, don't go to someone who trusts you and say, "I just want to confess to you that I have been having all these evil thoughts about you."

This list does covers the basics but is by no means exhaustive. There are good books on the subject, but the best book to read is the Bible. Look at the example of Jesus and remember that the blood of Jesus is enough to cleanse your sins.