Basic Slots or "flat tops" have a constant top jackpot payout that does not change no matter how much the machine is played. Basic slots tend to give smaller wins to keep you in business, extending your playing time. Basics come in several different paying versions, most of which require maximum coins to hit the top jackpot. Three features that should dictate any basic slot players' search and quest to stretch their gambling bankroll are:
1) Single payline..stay away from multiple paylines, too expensive. Better to play multiple paylines on Bonus Slots when a second screen bonus round offers additional winnings: see Bonus Slots.
2) Two coin maximum basic slot. A 3 coin machine may show a payout of 120 coins for the same combination as 80 for 2 coins, but remember, you had to gamble an extra coin, each spin, therefore, the payouts are generally equal. Players should invest more of their playtime and money in the preferred 2 coin machines, equaling more pulls and more chances to win a jackpot.
3) Seek out those slots that pay double jackpots on certain pay-line combinations. The principle of this "double" symbol is very simple, whenever it appears on the payline in combination with any other symbols which normally would have made a winning combination, the payoff amount is doubled or multiplied: e.g. Double, Triple Diamond, or Red, White & Blue7's.
Look closely at payout schedules posted on the slots-- not all slots will double and quadruple all pays and not all machines will have double jackpots win possibilities.
Don't confuse them with joker machines or wild cherries or any other symbols noted on the machines payoff display as being "wild". Symbols identified as being wild sub for any other paying symbol. but do not double the payoff.
You will almost never find these preferred slots in the same carousel. Carousel slots are mixes of good and bad machines. The thinking is that people will be attracted to a carousel if they see one player cleaning up on the good one.
If a casino advertises specific slots as 98% return, this will never mean that for each $1 you put in, you will get back 98 cents. A lot of first time players make this mistake. This means that over the fiscal year life cycle of that particular slot machine, it will average payoffs equal to 98% of all monies put through. Casinos advertising high return slots or 100% 'certified' slots, usually dollar slots, must tell you whether all the machines in that carousel are high-return slots or just one or two slots. Slot hosts or change people at these specific banks/carousels should know and if not; as a consumer- ask, ask and ask again until you get an answer.