Building relationships is effective youth ministry. It is one of the most important, if not the most important, thing that you can do. Kids will be looking at you. They will be watching to see if you practice what you preach. If you are married, a healthy marriage is one of the most important things that you can model in front of your kids.
Availability is next to godliness.
Godliness and a vital relationship with Christ is the first and most important criteria for being a volunteer. The next most important is your availability. Kids know that you love and care for them when they know that you are sacrificing to spend time with them. Students need affirmation. In today's world most adults are too busy to pay much attention to teenagers.