How do I decide how much to wager on a play?
There are two things you must decide.
First is the amount of your betting bankroll. What I recommend is to set aside an amount for wagering that if you lose it all it will not be a concern for you.
Secondly, you then need to decide whether you wish to take a conservative approach or a more aggressive one. The range of amounts to wager should be from 2% to 3% of your wagering bankroll.
From experience, I can tell you 3% produces some wild swings that unless your experienced might cause you concern. In addition, the higher the % the greater the risk of ruin.
2%, on the other hand, is a good number to use. Your swings will be much tamer and your exposure to negative variance will be a lot less.
Your bet size will rise and fall depending on the amount that is in your wagering bankroll. I adjust my bet size daily.