There are indeed various things that you should consider before you start playing a new slot game. The first thing you should find out is what return to player (RTP) the particular slots game offers. Return to player is simply how much of the money being played will be returned to the players.
This is not an individual percentage, an RTP of 97% will not guarantee you that if you play $100 you will at the very least win back $97. It depends on many factors such as how long you play and how much you stake per line. The RTP is the average percentage worked out over play time of the machine, not per session of your play time.
Choosing your slots game carefully can have an impact on your likelihood of winning. Different slots games pay out differently, the more lines a slot has in play the more it will cost you per spin, however the more lines also means the more possibilities to win the game. Traditional 5 line slots games will often give three or more different pay tables depending on your stake.
The higher your individual bets, the higher the possibility of winning the game. Newer game style slots can have any amount of lines, a 30 line slot with one credit per line at the minimum stake will not cost a lot per spin but the payout will be low because the actual amount you are betting per line is very low. However these types of slots allow for multiple wins on several lines stacking up your winnings per spin (if any).
You should always take a look at the pay table of your chosen slot game before you play as some games simply have lower payouts than others, some will pay out for as little as two left to right matching symbols instead of three, making matches more likely. The things you should look at are the pays, the lines and the minimum and maximum bets. By studying these you should be able to work out the potential wins for any pay line and work out which machine to play.
Another thing to consider is the type of game that you play. There are many progressive jackpot style games, these may be tempting but you should take into account that your chances for scoring the jack pot are extremely low and in most cases they are dependent on you playing at maximum bets.
Progressives can also have less winning combinations than standard slots games, with lower payouts for higher matches. Unless you are going for a high jackpot payout these style of games are not going to be suitable for you. Most players who want to play regularly and come away with winnings regularly should play slots that offer lots of pay lines and mini, in game bonuses such as free spins and scatters.
All of the above information can help you to improve your game, while online slots will always remain a game of chance, developing a method for picking the best games with the highest potential payouts for the amount you are willing to bet per spin as well as knowing how to quit while you are ahead or cut your losses will improve your performance overall.