My advice
1) Don't advertise campus-wide. Limit your area to something definable, such as 1 academic department or 1 dorm building. Specify how many people you are looking for e.g. 8 to 10.
2) Have a way to vet people. Don't advertise open or drop-in game to start. Use e-mail or message drop box contacts only.
3) Play in a semi-open area where you can get some walk-by exposure, like many an empty classroom or office or cafeteria corner.
4) Don't use physical cash. Keep a ledger and do money transfers by Venmo or other fee-less system.