Slot machines are going to vary on the payouts and how they can be played. Before you go into a land casino or play online you should research your options. When you are doing research you will learn about the machines that have the higher payout. Some machines boast at having 98 percent return on 100 dollars, but they can be hard to find from just an advertisement. So if you read up on the machine you can safely pick one that payouts.  
  
To pick the appropriate slot machine consider the number of paylines that machine has. If the slot has one payline you are not going to get the 98 percent return. You have over a hundred symbols to get for each spin, meaning one payline is minimal. For better results the more paylines you can play the better off you will be for slot strategy.  
The most paylines you can have on a machine are going to be 20 with a five reel. This offers you the most options. For example if you spin the machine and bet 20 cents because it is a penny machine you can at least earn a little. Say you bet 20 cents and ten paylines paid off. You don't always lose ten cents for only having ten paylines payout. The symbols are going to tell you the pay tables.  
Some symbols are wild, scatter symbols, unlock bonuses, or offer a multiplier. If you get a multiplier of 2x on one payline you get 2 cents. So you can make more than you lose even if all paylines don't payout.  
Another thing you should consider in your strategy is playing with progressive jackpot machines. These machines offer a high return because they want you to keep adding to the pot. If the pot doesn't win this attracts more customers so they attempt the game. If you are getting a better payout it is also going to attract more customers. So the chance to win a million on top of getting a better payout just makes sense.  
In the slot machine world you need to always place the max bet. Don't get confused by max bet versus the maximum amount of money you can play. In a progressive jackpot you need to place the max bet to win. However the max bet is the amount of coins you need to play per round. For the three reel single payline slot this is usually 3 coins. These three coins can be the lowest denomination the slot machine accepts in order for you to win the progressive jackpot.  
The maximum amount of money you can bet will vary from $15 dollars to 100 dollars depending on the denominations accepted by the machine.  
The progressive jackpot is just one part. All machines have a max jackpot, but some don't increase the payout for pgslot that jackpot.  
If you understand these hints you can have a strategy that keeps you playing and winning most of the time.