God will speak to your heart.
If you are a Christian, and God sees that you are about to commit a sin, our Father in Heaven will ask the Holy Spirit to convict you. You will feel that what you are about to do is not good in God’s sight. Many Christians who sin against God later testify that something within their hearts (the Holy Spirit) prevented them, but they failed to listen.
Something will obstruct you.
Our Father in Heaven will send something that will obstruct your movement into sin. For example, your car may break down, or your dress may mysteriously get torn. You will be forced to go back home.
God will use another person to talk to you.
Sometimes God may send to you a person to talk against the sin you are about to commit. This person may be a friend, a relative, or a stranger.
God will warn you in a dream.
Our Father in Heaven may warn a Christian in a dream that what she is about to do is a sin. God did this to a man called Abimelek (Genesis 20:3). This man was preparing to sleep with a certain woman when God appeared to him in a dream. In this dream, God warned Abimelek that the woman he wanted to sleep with was already married. Abimelek became so afraid that he politely requested the woman to go peacefully.
God may send you his angels.
Our Father in Heaven loves you so much. He does not want you to go to Hell. God may send you his angels who will do everything they can to prevent you from falling into sin. This is exactly what happened to Balaam in Numbers 22:21-27.
God may change your mind.
At the last minute, God may change your mind. You will find yourself not falling into sin.
God may bring a Bible verse within your mind. As you reflect on that verse, you realize that what you are about to do is sin.
Visions and dreams of Hell.
God may show you dreams or visions of Hell or destruction. Such dreams and visions will prevent you from sinning against God.