You want to look at angles in the leg, shoulder and hindquarter, and you want a foal that is relatively well-balanced. If you can see foal photos (3 days, 3 weeks, 3 months) they are also a good guide.
OP if you're from aussie-land anything you're looking at that has been weaned is already a yearling. Or it's been weaned too young. You want to look for this year's foals and wait a while, unless you specifically WANT a yearling.
Bloodlines are important. Parents' performance records? Conformation? Temperament? Especially seeing as you want an eventing prospect! I like clydie crosses for eventing, but not particularly sold on stockhorses or appies (have noticed a tendency for them to be a bit downhill) bar the occasional spectacular individual.
I just recently ventured into weanling-ownership myself and my filly is by an unproven stallion (the stallion was not even started under saddle, let alone competed, but has a nice jump), first foal from the cross, but I was looking for nice clean straight legs, good angles in the shoulder and hindquarter, and ok overall balance. And TEMPERAMENT. It is VITAL to get a foal with the right temperament for YOU, especially for your first. My girl is really pushy, but I chose her for that, because I'm really dominant and I don't want to frighten an already timid foal. She's not a spooky sort, in fact she is amazingly chilled for a foal her age. But definitely not lethargic. That is REALLY important!
You need to be able to tell the difference between chilled out/relaxed and lethargic! It is so easy to fall into the trap and end up with a foal that was drugged when you went to see it, or worse, a foal that's real sick.
I am lucky, I chose the foal most people advise to avoid - crossbred, totally unregisterable even with colour societies, from an unproven sire whose conformation was less than ideal. But I also chose the foal with nice clean straight legs, nice shoulder and hindquarter angles, and GORGEOUS movement. She is like a mini-warmblood. She's a bit of a fugly at the moment but that's yearlings. Like I said, you'll ideally want to see foal photos (I couldn't even see those! bit of a blind stab... hoping she turns out nice), especially if the seller is claiming that the foal is in the ugly stage.
In a foal at 3 days, 3 weeks or 3 months, you're looking specifically for good angles, nice even build (shoulder, ribcage and hindquarter should all be roughly the same size and the foal should not, at these ages, be downhill at all, or too uphill), and CLEAN, STRAIGHT legs. Great hooves are a MUST. You will ideally want a foal with some length of rein, but they are often short in the body and neck for their size. Ideally the top line of the neck will be longer than the bottom line, and the other way around for the body. I like a short body with a slightly long neck.
I, too, ride eventers/showjumpers, and I specifically bought Satin hoping she would mature into a nice eventing pony. But when buying a foal, you do need to keep in mind that you might end up with an unpleasant surprise down the end of the line. And you are guaranteed to look at your foal at some point and wonder why in heck you bought it... I'm at that stage with Satin at the moment because she is well and truly into the yearling fuglies.
EDIT; the person who suggested looking at previous progeny of both parents is very wise. It is a VERY good idea. Unproven stallions, mares, or crosses are a HUGE risk to take, because you honestly never know what you'll end up with... At the same time, though, I know a pair of ponies that are full brothers - chalk and cheese, my friend! One is absolutely stunning, stallion quality for sure (but sadly gelded as he is unregistered), and the other is, well, fugly. That's putting it politely!
Last edited by blue eyed pony; 10-08-2011 at 01:11 PM.