No horse is conformed perfectly. Remember that in examining horses the purpose is to exclude those with physical faults your team considers unacceptable.
Overall, when examining a horse you should consider balance, bone, intelligence and athleticism.
Balance - Is the horse well-proportioned? Does the frame suit its muscle?
Bone - Does it appear to be substantial - not too light?
Intelligence - Does the horse seem in control, aware of its surroundings, alert?
Athleticism - Does the horse look physically fit and capable?
Remember, every horse has some physical fault with regard to pedigree and conformation. The art or science of evaluating a horse is deciding which of those faults are less likely to adversely impact the intended use of the animal. It is helpful to know something about the pedigree of the horse as it may relate to a particular horse's conformation. Some sires pass similar conformational faults to offspring, with some of the faults having little or no consequence with respect to their racing success.
Everyone has different thresholds with regard to what constitutes acceptable faults. Establish your own thresholds, but be realistic considering your budget.