Properly managing your bankroll is important so that you don't run out of chips if your desired cards don't show. You must always play with realistic bets according to your balance and only with expendable money. When playing in cash games you don't need to plan for more than 1/20th of your balance on a single session at the table. When playing in tournaments expect that your bankroll isn't less than 40 tournament buy-ins as there is a higher variance in tournaments.