It is really hard to safe gambling because you will spend a lot of money with it and that is bad because if you lose that it would be all wasted and that must not happen to you.
You can play with some small amounts if you dont want to lose that much money but the chance to win is also smaller.
Having a big bankroll and playing it on a small amount is good, but you still have to control your emotion so you don't get greedy all of a sudden and going all in.
Really though, the only thing you need in gambling is self-control.