Look beyond the theme
Paytables explain winning combinations, special features and bet sizes. Read them before playing: similar-looking games can work very differently.
RTP is a long-run measure
Return to player describes a theoretical average across a very large number of plays. It is not a promise about your session. Check the information panel for the specific version of a game.
Volatility and your budget
Volatility describes how uneven results can be. Every spin is uncertain; a losing streak does not make a win due. Decide what you can afford to lose and stop at that limit.