I am going to describe this process as though you are saddling a young horse for the first time with extra care being taken not to alarm the horse. The process is the same for a horse who is accustomed to being saddled except that you do not have to be quite so slow and easy.
Before I tack up, I groom my horse. You don’t have to give them a bath and a show grooming, but you do need to get the dirt off, especially from areas that will be covered by tack. If you put a saddle on a horse with dirt on his back and his girth area, you will likely end up with a sore spot. I use a vacuum cleaner in the winter when my horses are fuzzy because it is quick and effective, but a rubber curry and a stiff brush does just as good a job.
It is good to have your horse safely tied (with a quick release knot) before you start to saddle. Whether you are riding English or Western, the procedure is the same, although the actual way you tighten the girth is different. Although Western saddles tend to use detached pads, English saddles tend to have their pads hooked to the saddle. I start out making sure the horse is ok with the pad. This can be done by simply flopping the pad around on the horse’s back as you prepare to position it. If you get any nervous reaction, you know that you need to back off and spend some time getting your horse used to things on and around its back. As you position the pad, put it much further forward, well in front of the withers, and then slide it back into proper position. There is a spot where it stops and settles, and that is the proper location for the saddle.
Next secure the stirrups either by running them up (English), or hooking them on the horn (Western) and lift the saddle into position. Again, it is best to place it a bit forward and then gently slide it back into position so that the hairs are not pushed the wrong way. Horses prefer having their hair smooth, and if you rub the hair on your arms the wrong way, you will realize why.
When the saddle is in the correct position, go to the off side and release the girth (or cinch) and let it drop down. Go around to the left side and reach under to make sure the girth is in the right spot. You want the girth to lie behind the elbows of the horse but in front of the area where the barrel starts to get larger. There is a perfect little area where the girth fits nicely, and you want to make sure you place it there.
It is important to be both quick and gentle in starting the girth. I like to get it tight enough so the saddle would not slip if the horse should jump, but not nearly tight enough for riding. You do not want to approach tightening the girth as though it is going to be a problem, because horses take cues from your behavior, but rather matter-of-factly tighten it sufficiently to keep the saddle secured. The methods of tightening English and Western saddles are different, but both should involve smooth even pressure as you raise the girth buckles (or cinch ring) to the appropriate place.
When the saddle is properly fitted, you will be able to get your hand between the horse’s wither and the pommel of the saddle, and the back of the saddle will ride evenly on the horse’s back.
At this point, I lead my horse to a safe place to mount, allowing the horse to get used to the girth, and to expel any air he is holding. Before mounting, tighten the girth as tight as you can without having to strain. You do not have to cut the horse in half to have a secure saddle, but you do need to make sure it is tight enough to not slip when you mount.