The percentages can be anywhere from 90% – 99%, depending on the game type. Most likely any slot machine you’ll play will have a certain payout percentage configured on it. From there, go ahead have a look at the game’s pay table to see what kind of features are being offered and what you need to do to trigger them, such as progressive jackpots, Stacked Wilds, Sticky Wilds, Mini Bonus Rounds and more.
See what kind of characters are being used and check out the music and sound effects. You can do this by checking out the various themes on the games. One of the basic rules you should consider before playing slot machines is to find a game that appeals to you the most.