Personally I will prefer physical casino to avoid all this scam issue, but if you prefer online I guess you should put this factors in check. First is the security level  they operate on so that you don't run in to scam or vulnerable site, checkout the users Interface so that navigating to place your games will not turn to a work of it own, the rate with which they pay out winning to their customers. And consider also customer care service because you will always need their assistance.