As in all walks of life there are unwritten rules and guidelines when it comes to playing casino games and placing bets with the casino or even family and friends. Much like the Ten Commandments written in the Christian bible, there are a similar ten specifically for gambling.
The first is you should never cheat. Not only just cheating undermine the integrity of the game you are playing but it also makes it a much less enjoyable experience for you and those you are playing with. On a slight tangent is the fact you should always honour your gambling debts. If you have run up a tab or placed a bet that loses it is your problem and you should pay up, no two ways about it.
Probably the most important to realise is that you should expect to lose. Casinos and bookmakers are not in business to give you money and even using the best strategies and rules available to you will almost always see the house have an edge over you, no matter how slight.
Many gamblers lose vast sums of money by going on a hunch or feeling rather than trusting the odds and probabilities of the game they are playing. All casino games revolve around mathematics so learn the odds and play accordingly. Tagged with hunches and feelings are betting systems, which simply do not work for casino games. As the house always has an edge, each bet you make has a negative expectation so using any system will still see you lose, although at different rates, in the long run.
You should also never hedge you bets by taking insurance in blackjack or betting on any craps or 7 at the craps table. These type of bets usually stack the odds hugely in the favour of the house and for that reason alone they should be avoided.
Finally, understand the expected etiquette for each game you are playing and act accordingly. For example, if playing craps it is unlucky to ask to change dice so do not do it. Also, calling for a seven or a card that would see others lose, again in craps, is frowned upon. Understand the rules and what is expected of you, adhere to them and both you and your fellow gamblers will have a much more enjoyable time at the gaming tables.