Base Bet Plus Square Root
This horse race betting method has been around for about 20 years, maybe longer, and was popularized by James Selvidge.
For an in-depth study of the approach, see his book - "Money Management" published by Jacada Publications ( I don't know if it's still available ).
The betting method can easily be tested in real-time with a small bankroll. Selvidge recommended the base bet be only $1.00 (with multiple "flows" going on simultaneously), but you can use $2.00 or whatever base amount you want.
BB+SR is good for the small bettor. It is a conservative race betting approach that allows a steady rise during an average winning series, yet protects hard-earned bankroll profits when a losing streak is encountered after good profits have been accumulated in that series (this quite unlike Kelly and some other methods).
Why not just flat bet? This is a better question than it might at first appear to be. Complex money management formulas often end up with a lower ROI on a series of wagers than just flat betting would have done. The thing is, you need to look at the combination of ROI and total profits gained. Using a flat bet of $2.00, or $20.00 or whatever - through a long series of bets, may very well earn a higher ROI, yet while gaining far fewer profit dollars than another money management method (because you bets are not escalating as you gain profits).
The BB+SR horse race betting method in a nutshell: Your next bet is $2.00 (or whatever base bet you choose) plus the square root of any accumulated profits. No profits? Then the next bet is the base bet amount only. (you'll need a cheepo calculator with Square Root function)
This horse racing betting method needs "doing" before it becomes clear, so lets do a sample.
The series of bets below were from Horse Racing Gold "Daily Best Bets." These were all the bets for the days listed where the Best Bet horse went off at 3/1 or higher. These are consecutive days and races. This is a very good series. I could have chosen, of course, other days that would have been either better or worse.
Key: bb = base bet, sr = square root, p/l = profit or loss (race and total)