Not all sin condemns you to hell. Only serious sin. These are sins that can be committed only if you are firmly convinced that God is so horrible to you that there is no way you could stand being with him for eternity. Because your will is that you not be with God, you will not be.
You do not go to heaven with sin. You will be cleaned of your sin in the "waiting room" to heaven before you enter.
Small sin is to be avoided because it hardens your heart and turns cold your desire for God. Serious sin is a decision to reject God; this kind of sin corrupts you so much that you don't want forgiveness and you don't want God. God respects your free will and separates you from himself.
The fact that you can form the concept that trusting Christ is an important step in life tells me that you are far from serious sin. Follow your conscience, your internal sense of right and wrong, justice and injustice. This will lead you to Christ.
Resolve to avoid the small sins, too. When you stumble pray for forgiveness, not out of fear of punishment, but because God deserves your love and loyalty. Then go on with your life.