#1: check the seller's references. I can't stress it enough. Knowing that the foal was well-cared for from conception to weaning and selling to you is a great peace of mind that they at least have a good start to grow into a healthy adult in your hands.
#2: Have a look at the foal from birth on (getting good, clear photos, clipped if possible) and both parents. Photos of siblings, both full and half helps, too. This gives you more of an idea of what to expect as a mature horse. Temperament is important, and having had some ground manners instilled is also a bonus. Not necessary, but it is helpful if they at least know how to tie and get their feet trimmed as well as leading.
#3: Depending on the intended use for your foal, get guarantees in writing as well as signed. For example, if you want an eventual breeding stallion, get a GOOD guarantee of fertility as well as testicles both descending. Bite is good to have guaranteed also, but if you just want a pet, don't worry so much over it.
#4: Paperwork. Depending again on the intention for the foal (this goes along w/#1), you will want registration papers. Make sure the mare is ON the stallion report if there are not yet registration papers in existence. If they are "in the mail" you need confirmation of that, and that all is in order for ownership/transfer.
#5: Training. You have a big job ahead of you in training and raising your own. This is a pro and a con. YOU get to shape your horse's brain, and give them a good start in a sane and sensible routine. You will both bond together and learn about each other, whether is just be for handling purposes such as tying, leading and grooming, or for eventual performance.
#6: A definite PRO is to go out and pick the gender and color YOU wanted. No "roll of the dice" with shape, color or temper, and no risk to your mare or the foal.
There are some beautiful foals from '06, and I only wish I was in the position to truly shop.
Happy shopping!
Liz M.