If some of your visits have been less than fruitful, don't despair. You will learn too. And you will have many more opportunities to reach souls for Jesus. Don't give up! Keep going, and as you go, be sure you also keep praying. God WILL USE YOUR LIFE... for you are going in His will...in obedience to His command. "Go ye into all the world and preach the Gospel."
I also remember way back when I first began knocking on doors for the Lord that I was ready to go to my first house. I parked my car and slowly walked up the steps and stood in front of that door. I had tracts in my hand and a plan in my mind, but as I raised my hand to knock something happened.
What an experience! I still remember it vividly. Yet, years have passed, and I haven't quit. When you are hit with that fear, that intimidation, and yield to it...life is not over! Just try again! Keep on going. The Lord will be with you. You can do it, and you need to do it, because you are a "SENT-ONE"
What would happen if everyone in your church would go witnessing for the Lord for one hour, even twice a week? It would change your church. It would change your people. Think of the hours that are wasted each week on non-eternal things. Check YOUR priorities and remake your list with witnessing at the top, or close to it.