GNU Terry Pratchett
Technoblade never dies
The starting horses suck. So as soon as you have enough money, buy a better horse-- not necessarily *much* better, but at least a bit, and preferably pre-trained and equippedTo increase your odds of winning without manually going through every opposing horse's skills, get a decent horse and leave their worst skill completely untrained. Pick a competition type where the first skill it asks for is that worse skill, but make sure the other necessary skills are very high; this way it shows easier competitions, where your other skills are out of proportion to what it expects, especially if you pick competitions open to all horses and not just your breed
Use the equestrian center (once you unlock it)! That is the single most reliable money-maker without divine horses! Raise cows! Sell leather if you're short on patience, otherwise take the time to craft it into expensive things like whips and saddles!