Call others into the ministry. Rather than "recruiting volunteers," focus instead on the idea of "calling" individuals that you discern have gifts for ministry with teens. Invite these individuals to meet with you one-on-one and share with them the gifts and qualities you have observed that could help them be successful in nurturing the faith journey of youth. This "personal approach" is immensely preferable to putting out a public call for volunteers, which often results in people coming forward who have the best intentions but who are also totally unsuitable to serve with teens.
Build on your own weaknesses. Do some real soul-searching and make a list of the things you are not gifted at but which would be a blessing in growing a healthy youth ministry. Not good at organization? Find someone who is! Not into sports? Find someone who is uniquely gifted to help teens in this area. Are you great at details but sometimes missing the big picture? Seek out those who can help your ministry dream and vision.
Think out of the box. Despite what most churches might think, you don't have to be a male in your early twenties with a goatee, slim waist, and proficiency in ten sports to be a great youth leader. Help your youth experience the diversity of your church when seeking adult leaders. Senior citizens can be great with youth! Married couples and single people each bring their own unique perspective. A college/grad student can add a whole new dimension to your team. With great care and thoughtful boundaries, occasionally even a parent of one of your teens could be a real benefit to the team. (One caveat: when inviting parents to serve as adult leaders, I always check with their teens first.)
Ask your youth. It never hurts to find out who your teens would like to see serving with the youth ministry. Even better, bring a teen along when you talk to a prospective helper. Adults are sometimes cautious about helping if they aren't sure whether or not the kids really want them there. Hearing the invitation directly from the mouth of one of the youth can go along way to helping an adult make the choice to become a regular part of your ministry.
What others would you add?