He speaks to you through His Word and through parents, pastors, and teachers-- even through your own conscience. Be alert to what God is saying. When it's different from what your friends or family members tell, be ready to say no to them and yes to God.
Acts 5:29.......Then Peter and the other apostles answered and said, We ought to obey God rather than men. Deuteronomy 12:32.. What things soever I command you, observe to do it: thou shalt not add thereto, nor diminish from it.
When you know He's prompting you to do something, don't hesitate. Obey immediately.