Copied from a horse gambling forum I read but apples to this question as well, cite #5 for your answer.
These are some betting/discipline rules that I enforce in my own play.
Some of them are obvious, and some may not be; I swear by all of them...and they have made a big difference in my play.
I pass them on to you, hoping that they may be of some use...and -- if you are so inclined -- I would ask that you add some of your own...
1.) LEARN TO PASS RACES...LOTS OF THEM.
Most races don't deserve to be played. If you spot overlays in almost every race you see...then you are playing this game wrong.
2.) BECOME A SPECIALIST.
The best thing about full-card simulcasting is that we can bet on our favorite types of races...and still get all the action we can handle.
3.) DON'T KEEP SCORE BY THE DAY.
Even the best horseplayers have more losing days than winning ones. Don't make a bad day worse by trying to get even.
4.) DISCIPLINE...DISCIPLINE...DISCIPLINE.
Lack of discipline has kept some of the brightest handicappers in this game BROKE...for MANY years. At the end of the day's play ask yourself THIS question:
"Did I do exactly what I planned to do today...or did I let my emotions affect my play?"
If you didn't keep to your gameplan, then the day was a FAILURE...even if you won.
5.) IF YOU TAKE BETTING SERIOUSLY...GAMBLE ALONE.
Tom Ainslie said it best:
"Winning horseplaying is a solitary activity; the more social it gets, the less profitable it becomes."
Pittsburg Phil never bet a dime when he had friends accompany him at the track.
If you consider yourself to be a better player than Tom Ainslie and Pittsburg Phil...then feel free to disregard this advice.
6.) SET A PREDETERMINED LIMIT TO THE AMOUNT YOU ARE WILLING TO LOSE IN ANY ONE RACE...AND STICK TO IT.
Don't get into the habit of "loading up" on the "sure things". The name of the game is limiting your risk. It sounds easy...but it took me 20 years to learn.
7.) KEEP A BETTING DIARY.
Not only to record your plays, but also to write down any thoughts or opinions about your play during the course of the day.
Our memory is not to be trusted.
8.) AVOID TURF PARADISE LIKE THE PLAGUE.
Trust me on this one...

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