The first step is to realize that God actually wants you to resist temptation -- because He loves you. Once you understand how much He loves you, you'll really want to avoid what's wrong and do what is right.
After all, God isn't like a harsh policeman or a cruel judge, just waiting for you to get out of line so He can punish you. Instead, He is your loving heavenly Father who knows what is best for you. The reason He wants you to avoid sin is because He knows how much it damages you. If He didn't love you, would He have sent His only Son into the world to die for you? Ask Him to come into your heart today. The Bible says, "For the wages of sin is death, but the gift of God is eternal life in Christ Jesus our Lord" (Romans 6:23).
Then ask God to help you take practical steps to resist temptation. If certain "friends" tempt you to do wrong, avoid them. Stay away from places or events where you know you'll be tempted to do wrong. Ask God instead to help you fill your life with good things.
Ask Him also to lead you to a church where you will hear God's Word, and can meet people who will encourage you spiritually. The Bible says, "Flee the evil desires of youth and pursue righteousness, faith, love and peace, along with those who call on the Lord out of a pure heart" (2 Timothy 2:22).