The best way to increase your odds of winning on a slot machine is to not play. The probability of winning on any spin of the game is set by the game's program, and nothing you can do will affect that. The game is always set so that in the long run the machine will pay out less than what is wagered.
You can pay with a previous payout ticket, your member card, or cash. Often (if not always), the previous payout ticket will go in the same slot the cash can be inserted. Most machines takeR$5,R$10,R$20,R$50,R$100 dollar bills, though some also takeR$1, too. These areas will be lit up and unmissable.