The arithmetic
How to use a gambling strategy
A usable strategy has four parts: choose the cheapest form of the game, play it correctly on every decision, size stakes so a bad run cannot finish you, and record what happened.
Anything that promises more than that is selling something.
Choose the cheap version
Single zero over double zero. Three to two blackjack over six to five. The 96.5% build of a slot over the 94% one. Banker over player at baccarat.
None of these require skill and together they are worth more than any amount of clever play. Most of the cost of a gambling session is decided in the lobby.
Play it correctly, every hand
Blackjack has a chart and following it is worth around two percent against playing on instinct. Video poker has a paytable-specific strategy. Craps has three bets worth making and two dozen worth avoiding.
Correct play is boring and repetitive, which is why almost nobody sustains it. The people who do are the ones who treat it as a checklist rather than as a decision.
Size and record
Flat stakes at 1% of the bankroll. No exceptions after a loss, because that is where every system on earth goes wrong.
Then log it: date, game, stake level, time played, and the number you walked away with. After twenty sessions the log tells you what the hobby costs an hour, which is the only honest way to decide whether it is worth it.