I can't emphasize this enough. Go out to the races and observe what goes on there. Visit farms, training centers equine hospitals, wherever you can go. Go to seminars.
Thoroughbred ownership is a high risk business with huge highs and the very lowest of lows.
If you don't have passion for the business it will be very difficult for you to stay involved as the losses mount up. I think the most important thing is to decide what part of the thoroughbred industry most interests you. Don't forget the tax considerations because if you don't follow the rules, your business might be considered a hobby and you will have enormous tax liabilities. There are many different avenues to entering the business. I like the action at the track and really enjoy handicapping.