This is a very vast subject. I'll do my best! But for a nice chunk of info, I suggest heading to the small website that I added a link to below this answer. In the forum there is a topic about EC prestige. =)
Here are some of my main tips though:
- Start small. If possible, start with one DH box (it's the biggest kind, and you'll have 100% for box size prestige that way). Then either grow or buy flax bedding, for 100% bedding quality. And with only one box, you don't have to hire one, as Owlient supplies a free groom.
- While your job offers are open, hire temporary employees until the positions are filled.
- Only use fertile meadows for pasture, so the meadow fertility will be better. When they start to lose fertility, lay them fallow. Make sure you have at least 1 acre of meadow in pasture per horse boarding at your stable!
Those are just a few tips. Again, I'd head to Howrsekinz for more info on the matter, as it'd take too long to put it all here. XD