Slot machines can be tricky if you don't know what's going on. You have single, line slots, multiple line slots, bonus rounds, progressive jackpots, etc. Sometimes it's just easy to get confused. Then there's the point of what to play, which always varies. If you're playing a progressive slot you play the max coins so you have chance to win that big jackpot and quit your job. If you're playing a non-progressive, however, you shouldn't play all of the coins, because it won't increase your chances of winning.
If you want to make the most money, what kind of slot do you play? That is the base question that slot players want to know, and is a variation on the question that all gamblers ask: how can I make the most money? The answer is slightly difficult. It all depends on how much you want to spend, and even then it's not definite.
If you want to make the most money on the slots, you need to play the most expensive slots. You're going to win more on a $5 machine than you are playing nickel slots. It's just common sense. More money is being played on the $5 machine, so it's possible to pay more out. The nickel machines make up for payouts by being bright, having a tons of options and keeping the player in front of the machine for a long time. If you want to make the most money, you have to spend the most money, and unfortunately winning is never a sure thing in the casinos.