How do I pick a sure bet?

You don't but reading this page will help increase your odds.

Also, each turn's email includes a 'Best Bets' list -- this shows the upcoming races which have the most favored horses.

What do the racepts indicate?

Race points are given to winning horses and reflect position and difficulty of the race.

What does stress indicate?

Various activities add stress to a horse, including running a race, stumbling, breeding. Stress increases the chance that a horse will be injured in a race, or die. The genes for BONE and MUSCLE reduce the effects of stress. A low stress level is preferred. Resting allows stress to decrease faster

Why is it that you find races where most if not all of the field contains horses owned by the bank, and then my horses all get entered into the same race?

It’s difficult to spread your racers around if they are competing against each other.

Horses are assigned within each race type by descending order of claim price, then by their age.  So horses with the same claimprice  (eg, 0) will tend to be placed in races with other horses of the same age.   The bank always sets claim prices on its horses and always has its horses for sale at low prices, so you'd have to put your horse in that range to compete.  Of course, the bank never uses food and training above 100% so you'd probably have an advantage

Is age a factor in races?

Yes -- older horses accumulate stress and racing points. Horses must be 2 years old before they can race. Most horses reach their peak racing form at age 5 or 6