Volatility, theme and budget — consider all three together
Volatility refers to how often and how large a game pays out. High-volatility slots (such as Nolimit City's Fire in the Hole xBomb) win less often, but the amount is larger when they do. Low-volatility games pay smaller amounts more frequently — useful for keeping your balance going longer.
Choosing a theme is not just about looks — the entire bonus round experience changes depending on the theme. Cricket and football fans tend to feel more at home with sports-themed games.
Budget planning is the most important factor. Each slot has a different minimum bet. If you want to play longer on a smaller budget, choose a game with a lower minimum bet and set a firm limit for yourself.
RTP (Return to Player) is an important piece of information. For example, PG Soft's Fortune Mouse has a maximum RTP of 96.96% and Mahjong Ways 2 has a maximum RTP of 96.95% — this is the mathematical probability of how much the game returns over the long term, not a guarantee.