Instructions
Lead your horse out of the stall to a clear, level spot. Stand on the horse's left side and check the girth. This is the strap that holds on the saddle. Horses often hold their breath when the girth is first tightened. Pull the girth tabs up into the next hole or holes to tighten the girth.
Pull down the stirrup on the horse's right side. In an English saddle, they probably are both "run up" to prevent them from banging the horse's side when he was standing in his stall. Place your finger tips at the top end of the stirrup leather and measure the length of the stirrup along your arm. Adjust it with the stirrup leather buckle to reach just inside your armpit, in estimating more or less the correct length. Pull the leather around to keep the buckle under the leather flap or skirt of the saddle.
Adjust the left side stirrup in the same way. Gather the reins and hold the pommel, or front part of the saddle, with your left hand. Lift your left leg and attempt to place it in the stirrup.
Lengthen the stirrup a few holes if you cannot reach it with your leg. Pull the buckle so it is under the skirt and will not tear your clothing when you mount.
Place your left leg in the stirrup. Hold onto the far side of the saddle with your right hand at the back if you can reach it. If you hold the middle of the back of the saddle or cantle, you will twist the saddle. Use your right leg to spring and hoist your body up, and stand in the stirrup with your left leg. Move your right hand to the front and lower your right leg over the other side of the saddle. Sit down gently so you do not hurt the horse's back.
Place your right leg in the stirrup. Lift the skirt on the left side behind your leg, and keeping your foot in the stirrup, pull the stirrup leather up to shorten it until it feels comfortable. Sit in the center of the saddle and take both feet out of the stirrups and hang them down. The bottom of each stirrup should be in line with your ankle bone. Adjust the stirrups further to get them even if necessary.
Adjust the stirrup on a western saddle by pushing up the flat, hard leather tube known as a "slide." This will reveal the "blevin," which is a two-pronged type of fastener. Pull the leather out of the prongs and move it up or down, then replace the slide when you are done.
How to Make a Stirrup Longer for Ease of Mounting
Mounting a horse is a technique that takes practice. If you are short and your horse is tall, it sometimes is not physically possible for you to get your foot up into the stirrup from the ground to mount. You can use a mounting block if available or ask someone to help you. But if there is no mounting block or help, your only option may be to lengthen the stirrup on the left side so you can reach it with your foot.