Don't know if its the best way, but here's what I'm doing in my first game.
When I got enough cash to get the breeding kennels, I went out and started watching the auctions for older dogs. I got two four year olds. Neither is worth anything in the racing. I autorun the first six months and now its Nov. I think both ran one trial. But each has at least something decent in their blood lines (open winner and a Grade 1 winner). And both were very cheap.
So that's the start of my breeding program while my 1 and 2 yr olds run.
I'll have to see where that goes. If the dogs these two old fogies produce are any good or just worthless? Meanwhile, I'm watching the auctions for more breeders, and trying to get my young dogs to win a feature.
Since winning a feature is the only thing that counts for both money and trainer of the year, I figure I'll try that until I become convinced these dogs won't hunt. Then I'll retire them to breeding and look for some other dogs that might bring home a trophy.