ask in this forum is the best way to get info about any site or just try with low money 
All you have to do is research, just research and read reviews about the gambling website in question and you'll be able to arrive at an intelligent decision. Most of them are foxes in sheep clothing so their real trait will not be evident on the spot so you can rest th m with little amounts first.
I just prefer to read reviews about the gambling sites. And it's good to visit each of their threads, most of the popular gambling sites have their threads also here in forum, you will see people complaining or giving good feed backs about their experience to that casino. You just need to be resourceful.