Those are Indian casinos. Legally they can't arrest you, but that doesn't mean they won't. You also can't sue them in civil court for abuse or injury, which is what the usual deterrent is. If you are just a counter there is usually no incentive to arrest or harm you either, as all they have to do is tell the dealer to stop dealing you cards to completely eliminate the threat. But casinos hire some nasty, dysfunctional, and downright stupid people and you will occasionally encounter security personnel who will harm you just to show off, or because they think then they will get to be a cop or something. This game is not for the faint-hearted and I'd be lying if I said there was no risk of this, but it is rarer than the stories make it out to be and if you are smart you will reduce your risk of harm.
Smart: do not have anything on you that you wouldn't want to be arrested with. No weed, no paraphernalia, no gun unless explicitly legal. Do not fight, do not run, consider walking right out the door without cashing your chips if things look ugly. Lock your phone with a good password and do not unlock it for any reason, have it backed up and be prepared to abandon it.
Drink: I drink and treat the free booze as part of my pay. If it is normal for you to drink I consider doing so to be safe when playing. If you drink or smoke to alleviate the boredom of advantage play you will affect your health before you affect your play. Remember that drink can cause urgent need for the bathroom which can be a big problem in shoe games and the first time you have an Alan Shepard "Do it in the suit!" moment you will vow to never let it happen again.
Play: Low stakes to start of course. Maybe you can start with counting but flat betting the minimum anyway just to get used to it, then work in a small spread, and then insurance and some index plays. After a few nights it should be natural and easy.
Other players: You will have abuse heaped on you by other players at the table. Everyone has heard of abuse of counters by the casinos but only counters know about this so don't be alarmed. Like most addicts compulsive gamblers will blame everyone else for their problems, and every time you do a play the CG wouldn't have done and he loses the hand, it will be your fault, and you'll get anything from a friendly lecture, to dirty words, to outright dangerous and threatening behavior. Do not let any of it sway you of course, and how you respond to it depends on what works for you. Sometimes I ignore it, sometimes I engage in uneducated debate, and sometimes I convince him I'm a psychopath and he had better leave me alone.
Get out there and play!