Bankroll is the amount of money you have designated for gambling. Keeping your bankroll separate from your personal finances is a good way to avoid gambling problems. Bet Max is a button on the slot machine which gives you the option to play the maximum amount of coins the machine allows. This tends to speed up play. Comp is a bonus that a live casino offers players for continued play at one of their machines. It can take the form of free meals, shows or even cash rewards. The percentage amount of the house edge indicates how much the casino wins from every bet over a long period of time. Payback is percentage amount of each bet dollar, that is paid back. If you play the slot machine with 86% payback it means that it pays back 86% and 14% is the house edge. Remember that these amounts are taken over a long period of time.

You must know exactly the game you are playing.
Only the correct amount of money should be inserted into a machine. Your credits should be cashed out before you leave the machine.
Slots shouldn't be a stress for you, just enjoy. If you feel lucky increase your bets and vice-versa.