How could a teenage girl relieve stress and boost her confidence?

Self confidence: Finding an activity which is fun, and rewarding would help. Physical activity tends to help with stress and mood. Some ideas might be self-defense training, art, music, dance, sports (individual or teams), community service, etc. Most important is to find something that the teenager can relate to and is interested in, and so taking time to listen and show respect for their ideas is very important.

Relieve stress.: Talk about feelings ; address problems. Don't avoid them. Aim for 7.5 - 8 hours of sleep/ night. Daily physical activity is optimal in a green space. Eat healthfully. Cut out junk carbs, caffeine ; alcohol (or moderate). Try qi gong, tai chi, acupuncture, acupressure, homeopathy, meditation, yoga, exercise program, deep breathing exercises or progressive muscle relaxation. Teach her to love her.