What are the keys for mounting the first time?

The first mounting of a young or green horse is either a non-event or a crisis, and which one it becomes is determined almost entirely by the quality of preparation that preceded it. A horse that has been correctly prepared accepts the first mounting with curiosity and calm because nothing about the experience is genuinely new — the weight on his back, the movement of a rider's body, and the feel of a leg swinging over his hindquarters have all been introduced in graduated, positive stages before the rider ever commits his full weight. The preparation begins long before the first mounting day. The horse should already accept a saddle and girth without tension or resistance — not merely tolerate them, but genuinely accept them with a relaxed, swinging walk. A horse that is still cinchy or still reactive to the saddle moving is not ready for a rider regardless of how easy the mounting itself might seem. Stirrup desensitization is a specific and often skipped step. Long before a foot goes in the stirrup, the horse should be completely comfortable with the stirrups swinging against his sides and weight being applied to the stirrup iron while he stands quietly. Apply weight to the stirrup from the ground — lean into it, jounce it up and down, hang your full weight briefly and release — until the horse stands completely still through all of it. The mounting block is not an optional convenience — it is a critical safety tool. Position the horse at the block, stand at the horse's shoulder, and begin applying pressure progressively to the stirrup while leaning over the saddle. The horse should stand completely still through this process before any mounting is attempted. The actual mounting should be done slowly and deliberately. Gather the reins with light contact, place your left foot in the stirrup and pause, allowing the horse to feel that weight. When he is clearly relaxed, rise slowly from the block, swing your right leg over in a controlled arc that avoids bumping the horse's hindquarters, and lower yourself gently into the saddle. Sit still the moment you are in the saddle. The first ride should be brief, calm, and entirely successful — the goal is to establish the precedent that mounting is safe and that a rider on his back is comfortable and manageable.