Following are my commandments of gambling. I have said most of this advice elsewhere but almost everything I have to say about gambling in general can be summarized below.
Don't rely on hunches. Always make the mathematically best decision. On the players side is the unlimited use of clairvoyance and other psychic powers. The casinos have the mathematical odds on their side. Which one always wins in the long run? Expect your money will go up and down like a roller coaster in the short run. Even professional gamblers with an edge can have bad losing streaks as they ride the ups and downs of short-run bankroll fluctuations. Likewise terrible gamblers can do extremely well in the short run. In any form of gambling almost anything can happen on a short-term basis.
In general the harder a game is to understand the smaller the house edge is if you play it correctly. Your best bets are the more complicated games of blackjack, craps and video poker, assuming you play them wisely. Your worst bets are the simple games of pure chance like keno, roulette, and the big six wheel.
Set limites for the maximum loss per session and for the entire trip. Don't bet more than what you would normally spend for entertainment. Do other things besides gamble. Don't play drunk or tired.
Avoid the urge to insure against events that will caused you to lose or push rather than win. For example never take insurance in blackjack or bet on any craps or any seven in craps. The house edge on hedge bets is always very high. If you are afraid of losing then don't gamble.
There are plenty of charlatans promising systems that can beat games of luck like roulette, craps and the lottery. Most systems trade a lot of small wins for a few huge losses. In the long run it is impossible to beat the house at games entirely of chance.
It pays to shop around for the best possible playing conditions. In many games, especially blackjack and video poker the rules can vary from one casino to another and one state to another. Know what rules are favorable to the player and seek them out.
Among the worst bets in the casino are the $1 side bets in Let it Ride and Caribbean Stud Poker, carrying a house edge usually well over 20%. Side bets in blackjack and pai gow poker are not as bad but are also to be avoided. Also avoid variations in rules such as crapless craps and commission-free baccarat. Even with perfect play the odds are worse than the normal rules.
Don't forget that gambling is supposed to be a recreational activity. Like many things, what is enjoyable in moderation can be disastrous in excess. If you lose the ability to walk away from the table or machine at will then you shouldn't play at all.