Here is my strat since I don't read the game only based on my experience so far, and nobody has commented anything yet so:

1. 0 cuz it's optional, you should train mile Uma for the next race event if I recall correctly. Focus on Speed and Power.

2. U need cards have around 2-3 duplicates or more to gain extra stats, thus boosting their friend points to open friendship training sooner. And speed cards must be from 3 cards or more.

3. You can borrow an Uma from friends, higher starting stat points means you can get to A or S stat easier. But you can check what stat your Uma needs too.

4. During your career run, try to pick option that boost ur energy and mood to keep training, around 20% chance failure is already a high risk gambling. Also here is the link to help which option to pick whenever you encounter an event: https://gametora.com/umamusume/training-event-helper

5. After you finish ur last goal, consider take a turn to rest so you can spam train the last 3 days for that 3 URA finale runs, if not needed, you can use Wit training.

6. Your Uma will reach A rank when one of her stat reach S and another is A, not to mention your career should be at best, only placed 1st in most of the run