First, for all wagering, I would suggest betting the same value for every pick. Sometimes an iffy pick can be as strong or better as your strongest pick, so let luck play its toll.
Option 1 - Basic Numbers:
If you have a bankroll over $10,000 to wager I would suggest wagering 1-2% per play, or simply a set amount of $100 or $200 per pick.
Option 2 - Introducing Percentages:
Using 2% of your bankroll. There is one solid formula to follow for sports investing, and that is this: bet more when you win, bet less when you lose.
By using a 2% rule, you will always bet accordingly to your bankroll. If you have a $25,000 bankroll, then you would be wagering $500 a game, if you win a lot and your bankroll is now up to $30,000 you would be wagering $600 a game.
One thing about that though, is it doesn't change your bets sometimes as quickly as it should. Wagering can be streaky, just like Craps. You can be on a roll and hit 70% a week for 2 weeks, and then your next week only hit 40%.
Option 3 - Complex Percentages and Sliding Scales:
Basically it involves using your bank roll and win/loss streak. In short the formula is Your Win/Loss % over the last 6 games -55% * ( 2% of your bankroll) or (your normal wagering amount).
For example: wagering a constant $200 per game going 5-1 would mean you are winning 83%. You should now raise your bets (83% - 55%) 28% since you are on a winning streak meaning your new wagering amount would be $256 per bet.
If you are 3-3 that means you are 50% and not actually on a winning streak. The formula would say 50% - 55% so you would lower your wagers by 5%, so instead of 200, you would wager $190.
If you are 0-6 then you should lower your bets 55% (0%-55%) so your actually only wagering 45% of your normal amount or $90 a game.
The most common problem with gambling is people hate to lose and cannot accept it. They try to double up, triple up, or whatever they can do to instantly recoup their losses. This formula promotes responsible wagering and will neither make you rich over night or broke over night, but should always prove profitable in the long run.