I've visited other countries for learning and cross-cultural work, and I've done mission projects in my own community, and I even planned a mission trip when I was a youth director, but I went to seminary before the trip took place. When I got ordained, I was busy having babies, so the month-long trip to Kenya sponsored by the church I used to serve wasn't feasible. I wasn't involved in the church as a teenager so I missed the boat then too.
Jann Treadwell is a retired certified Christian educator and was the Association of Presbyterian Church Educators' 2010 educator of the year. Her book is Unbound: The Transformative Power of Youth Mission Trips, and it is both theological and practical.
Jann weaves together the "why" of mission trips (what makes them powerful and transformative) with personal stories and lots of nuts-and-bolts stuff as well. As someone on the outside look in on this whole experience, these stories are inspiring.
The appendix, full of release forms, suggested bible studies, and chore charts would be invaluable to someone planning a trip for young people that isn't just feel-good tourism but something deeper. Is that you? If so, give this resource a look.