This game.
Isn't all that hard or bad.
This is what I did.
Start the game off with Cat Chaser.
Go through races without betting on anyone.
Always train with "All Rounder" or "Dog Father" trainer.
Try to train before every race.
If you have money left over, buy anything that will help your dog.
Do not buy anything illegal.
Eventually I had every legal item and my dog's stats were all maxed out.
I was able to bet on my dog $5,000 every time and come out earning well over $50,000 in total.