I've seen lessons on the TV's in the rooms too. However, they just show you HOW to play. They do NOT show you all the stupid bets. For this, go buy a book on casino gambling and learn, really learn, how to play.
My game is craps. There are dozen's of different bets on a craps table but only about 3 that are any good. The best odds in a casino are on the pass and don't pass lines (and come bets) on a craps table. The house has a 1.41% advantage and if given free double odds your chances are even money. Generally, bet in multiples of 3 because of some of the payoffs they will round up to the nearest dollar, i.e. they don't give 50 cents.
One game on the ships I enjoy is face up black jack. It's not really a good odds game but I play minimum amounts and can play for a long time without losing much. In this game you get to see the dealer's cards. However, blackjack doesn't pay 3-2 it pays even, and the dealer wins on pushes. I can sit down with $20 and play for a couple of hours but on a regular blackjack table it seems to go in a few minutes.
I don't play slots at all. Well I should say close to never. They are programmed to pay off at certain rates and to my knowledge they are not bound by any U.S. gaming laws. In the state of New Jersey, the gaming commission allows a casino to set slot machines at a 17% advantage maximum. That means for every $100 dropped into the machine it will payout $83. Some machines payout more often than that. You've heard of machines that are hot? Well, it's true. They may be set at a 94% payout. I don't know if there are any regulations on cruise ships. Some people have done well on slots, I just don't bother.