Always read the pay-off information on each machine, particularly on Pay for Play machines. These are usually 3 coin Slot Machines with the first coin paying only on limited symbols, perhaps cherries and bars. The second coin pays on the next set of symbols and the third coin pays on any win. The big win is with the third coin. Many a player has turned up 3 sevens and stood in wonderment as to why they didn't get paid. They only put 1 coin in the Slot Machine and 1 coin won't feed the bulldog on a pay for play. Know what you are playing.
When playing progressive slots or 3 liners or 5 liners make sure you have inserted the proper number of coins in the machine. It can be very frustrating to see a line of 3 sevens and not get anything because you didn't insert the required number of coins.
Serious slot players must seek out the highest paying machines within the casino. Most Slot Machines pay out between 83% and 99% of the coins/tokens they take in. That doesn't seem to be an extremely wide variation, but it is! Whenever possible, seek out the machines in the 96-99% range and 'hit' them hard. As you might imagine, the number of casino Slot Machines that pay out at this level are relatively few when compared to the total number of Slot Machines in a given casino.
Wait....Watch....Learn. Sounds easy, but it's not. The hardest thing for any Slot Machine player to do is watch others having fun on the slots. However, if you can manage to wait and watch (even for a few minutes), you will quickly learn which Slot Machines have more frequent and larger pay-outs.
Talk to casino employees and fellow Slot Machine players. General casino employees are not trusted with the exact placement of the best Slot Machines. And, they wouldn't steer you to a particular slot machine even if they did know (since it's against casino policy). However, they usually do notice which machines seem to be paying out on a fairly regular basis. They will most likely not share this information with you unless you ask (especially if you tip them for the information). If you get a tip on a hot Slot Machine ... unclench your fist and tip back to that employee a dollar or 2, and if you win based upon what they tell you, tip them 5-8 % of your winnings. This will likely ensure more tips on great Slot Machines in the future.
Fellow Slot Machine players are also an excellent source for getting great tips. 'Regulars' to any casino can be most helpful in locating 'loose' slots. The fact is most slot players love to tell others of their successes. Listen to what they tell you!
Stay away from the giant, progressive slot machines; those that are linked to other progressive machines in other casinos such as 'Quartermania'. The odds are incredibly low that you will hit a jackpot on these types of machines. Quite possibly, the odds of you winning your state lottery are better than the odds you'll get playing the giant, linked progressives.
Play within your comfort zone. That is to say, if slamming coins/tokens into a $5 slot machine makes you nervous, then try a $1 machine instead. If pumping your hard-earned money into a $1 slot machine makes you break out in hives ... go to a quarter machine, etc.
Gamble in 'sessions'. Set a time limit or a spending limit (or both) and stick to it! If you are ever going to win playing casino Slot Machines, you must develop some self-discipline. You may play as many sessions as you wish.
Experiment with different playing strategies. There are several excellent Slot Machine playing strategies available to you.
According to industry sources, the casinos never place 2 loose machines next to each other. If you are certain that you are playing a loose machine, it would be wise to keep this in mind. If you're uncertain as to whether your machine is loose, it may not hurt to try the machines on either side of you. Just use extreme caution, and keep your personal pull-rule in mind!
Contrary to popular belief, the casinos do not 'hide' or move their best machines simply because people find and play them. The casinos want them to be played. That's the reason they exist! When Slot Machine players see and hear someone hitting a jackpot, it motivates them to pump more money into their own machine in hopes of hitting their own jackpot. It also draws other players into the general location of the jackpot where tighter machines wait to take their money.