3. Know what games you should play - that is really important, you should play only on those game on which you know that you can win the game, actually, you should choose the game that requires skills and techniques to win.
If you know, for example, about roulette, when you will never play it for sure
Only few games (like poker for example) needs some knowledge. Mostly, you need to bet and hope for your luck (if casino is honest).