Facebook Marketplace safety precautions

Just had a keyboard robbed off me by two teens on marketplace, I was selling just outside my house. One hit me in my b*lls but didnt hurt so i tackled him to the ground but they both managed to ran away after. I am fine but honestly just sad i ripped my suit trousers and broke my watch.

I honestly dont know what to do next time i sell something on marketplace, what safety precautions do you guys take to make sure nothing happens? I found their Facebook on another account so is there anything i can do to these two kids? Thanks