It seems a lot of people don't know what's involved in acquiring a foal and raising it to the age where it's usable for riding. As with keeping any age of horse, the first consideration is a safe environment. A pen with solid fencing- not barbwire!- is a good place to start. This can be board, pipe, or mesh fence, or some other material that a horse won't injure itself on. As with adult horses, a good source of water and a safe place to put feed, and some sort of shelter; a run-in 3 sided shelter is usually enough- like this one I had for Chickory and Andee (now owned by Fern Valley Appaloosas):
That's Andee on the left, Chickory on the right
Once housing is taken care of, that leaves your interaction with them. As a side note, it's always good to have a companion for them, either another youngster or an older horse. Until they are in the summer of their yearling year, most of what you do with them will be just getting them to lead nicely, pick up their feet, behave for your hoof care provider, stand tied, and tolerate grooming all over. If you plan on showing, you can add in training specific for the class you show in, eg. halter, showmanship, in-hand trail, etc. Since I don't show, I can't advise on what you can do for that.
As a yearling, you start introducing other things, such as trailer loading, ponying, sacking out.
Rio trailer loading at age 11 months
You also increase your expectations of good behaviour. If you plan to introduce them to riding in their 2 year old year, then in the fall of their yearling year you can introduce them to longeing for short periods (not too long because it's hard on their joints), sacking out with saddle blankets, and progressing to setting a light saddle on them.
Longeing Sassy as a long yearling
I like to have them checked by an equine dentist and get their wolf teeth pulled before they are 2. There is lots of ground work you can do with them as a yearling, like getting them to move away from the pressure of your hand on their side (imitating leg pressure). There are many books written on the subject of training, and I'm no expert, I just do what works for me.
None of this is rocket science, and there is no horse-whispering- mystery involved in getting a youngster prepared for their life as a good using horse. It's all common sense, and treating them like a horse, not tolerating bad behaviour just because they are cute, and laying out a training plan for them. If you aren't confident in being the first one on their back, plan ahead and save enough money to send them to a reputable trainer for at least a month. Remember, the ground work you do with them helps to build a bond and establishes your "place in the herd". Start as you mean to continue: if you don't want to be pushed around by a 1100 pound horse, don't let a 500 pound baby push you around. Establish boundaries from the get-go.
The end result will be a horse that you know the complete history on, one that you helped form, that you know inside out.
Me and Sundee, Coyote Belle's mama; my first heart horse that I bought as a weanling.