It's damn simple.
Never go to a casino with 100% of your bankroll, only take what you can afford to lose DURING THAT SESSION.
Never play above a fixed bet so to have something left to play more, and read it carefully, I said "to play more", not "recover it back". If you will go with a mentality to recover your losses, you'll definitely either deposit more or just play till the last cent of your bankroll is left on your account to try and recover, and then mess up everything by losing it all because you lose your control and go for unnecessary big bets.