If you're not comfortable with variance, you should bet 0$ each time. This is only partially tongue-in-cheek, since the only way to reduce variance is to bet l

If you're not comfortable with variance, you should bet 0$ each time. This is only partially tongue-in-cheek, since the only way to reduce variance is to bet lower amounts, but this will also reduce your expected return, all the way to zero at 0$ bets.