I'll give you the info in a nutshell that you'll find in virtually all of these 'slots secrets' books.
First they tell you to look for a slot that has only a 2 coin requirement for max bet, and a wild or multiplier symbol. Once you've found this (and they tend to be less prevalent than 3 coin or higher machines), play the $1 or $5 machines since they pay out a higher % than their .50/.25/.05/.01 cousins. And to check the payout percentages with the regulatory authority that covers the casino you want to play at.
Then it will go on to tell you to wager at the $$ level you feel comfortable starting with, say $1 and if you lose 1/2 your stake, drop down to the next smallest denomination machine, and repeat. Set a win limit and cashout when you reach it.
Then they go into the all important machine placement, which I think is no longer done in most casinos. Used to be they'd put the loosest machines in places to draw more customers, like near the doors, or at the beginning of a row, etc. I don't believe this is done any longer, and you're just as likely to find a winner by picking at random.
They also usually talk a little bit about the way a slot machine works. In an even smaller nutshell, every time you pull the handle or press the spin button, a random number generator pics a number which determines what combination of symbols, and thus the payout (if any) will be displayed. THEN it spins the reels and stops them on the appropriate symbols, but that part is all for show as the result has already been determined. Each spin is independent from the last, meaning you can have a jackpot spin right after a jackpot spin and the odds are the same for each spin. The payout % is controlled by a chip or switch setting inside the machine and can be modified by the owner (within certain ranges and depending upon the regulations in that location), so they can tighten or loosen any slot virtually any time.
I think the way to find the loosest slots is to ask one of the change people or better yet, the floor people who come and pay you when you do hit. Just ask them which machines are hitting and tell them you'll take care of them if you win (and then follow thru if you do).
They probably also tell to get a players club card and always put it in the slot machine before you start playing. It doesn't monitor your wins/losses, just cranks up the points based on playthru. This will increase the overall payout percentage by giving you a slight rebate for each spin.
That pretty well sums it up. Pretty secret stuff huh? (Send your $47 to me care of Casinomeister!)
p.s. I bought one of those e-books for ~$10 which is where I got this info from. Some of it is useful advice, and using the method of picking a machine right after I read this, I did get a pretty good hit on a 2 coin $1 machine, so it payed for itself.
