When I was needing the service, I would ask friends who they would recommend. I also called my church to see if they had any teens who were available and trustworthy. Following that, I met with them and asked questions, got to know them a little before asking them to babysit. I always asked if they had any training like Red Cross, or CPR, etc. Many teens who really want to earn money and provide good service will take these courses and let you know. However, I have to say that during the first early years, and I was very fortunate, I had a large family to choose from and they all wanted to help out. If your child is old enough, you can chat with them afterwards on how they felt the evening/day went with the babysitter. Ask questions that are non-intrusive, such as, "what games did you play with Annie?" It is always hard to leave your children with someone else but doing the research ahead helps alleviate those nervous feelings.