-Be on time for appointments with vet and farrier. If you remember something else that needs attention, call and ask before they come out. That’s how you keep them. Changing vets can cost big money. It seems like the newer vets around here charge a lot more money for a lot less experience. We use a semi-retired vet now. He still sees our animals because we treated him well. Changing farrier can be hard, too. If you miss, or are late for a trim, because you aggravated your farrier, it could set your horse back and cost more down the line.
-Keep a leather punch, bridle screws, and strips of leather handy and replace when you see wear, before it breaks.
-Safe fencing that keeps horses in and dogs out will save you money and grief. It is worth buying better fence materials.
-I use those black tubs to feed hay in so the horses don’t eat off the ground. I can dump them over before each feeding to get rid of sand or dirt. The baling machines can blow sand in with the hay.
-Fly spray saves you on vet bills. It’s worth the effort to spray them every day during the fly season.
-Supplements usually just make expensive urine.
-Get your horses out of stalls and pens at least every other day. Cooped up horses make trouble.
-Put the horse in the stall/paddock they get along best in; not the one you want them in.
I’ll bet every piece of advice people have given here has a story. It either happened to you, or someone you know.