You should first ascertain your own preferences. More bets increase your chance of winning large, but they also increase the likelihood that you will lose everything. In contrast, placing fewer bets will increase your likelihood of playing for an extended period of time with a modest bankroll, but doing so will also reduce your probability of winning.
If you do some arithmetic, you can begin to predict how much money you'll have to play with when you've played roulette for a time.
If you do some arithmetic, you can begin to predict how much money you'll have to play with when you've played roulette for a time.