Know what you are breeding for and then select the sire and dam with the right build and mind for that sport.
If you can go to an auction and find the same thing there for cheap, don't breed for it.
Even when you do everything right, there is still a chance of injury, death, or a subpar foal.
You can't ride papers, but if you want your horse to stand a chance of a good life if no longer in your ownership they usually help.
You can never garuntee you will always own your foal. Life happens. Set it up for success.
Always be aware of genetic diseases and testing for things like HYPP, HERDA, etc.
Proper vet and mare care are essential. Breeding is going to be more expensive than buying in most cases and is always less certain. Be prepared for emergencies.
Make sure you be willing to put the age appropriate training on your horses it needs while it is in your care. Either do it yourself or have someone else do it. It may be 'cute' now, but will it be cute when a full grown horse does it to you?
Most good studs will not be offering a fee of $200.