Next to your horse, your saddle is likely the most expensive part of your equine gear. For this reason alone, it pays to take care of it and do everything you can to preserve it. With only a few exceptions, most saddles are made of leather, and leather is essentially skin or hide. You can care for and preserve your leather saddle just as you take care of and preserve your own skin.
When you clean your saddle, you don't need to throw the entire arsenal of products at it each time. Many times a dusting will do. But when your fine used saddle needs more than a quick wipe-down, reach for tried-and-true products. While bath soaps and shower gels might be good for your own hide, they're not so good for the hide used to make saddles. In addition, grease, fats, and heavy oils also leave a coating that clogs leather pores. Plus, the now-sticky surface can attract and hold dirt that you will grind in the next time you ride. Stick with basic, pure, time-tested products.
When your saddle is drying, that's the best time to apply conditioner. Again, be sure all the soap residue has been rinsed off entirely first. There are many good conditioners on the market. When the saddle is not quite dry, apply a light coat of conditioner to both sides of the leather, then follow up with another light coat after it has dried completely. Conditioners help keep leather pliable and prevent it from drying out.
Oiling a saddle is best done infrequently. How often depends on what kind of riding you do and the condition of your saddle. Don't slather on the product when you do decide to oil. In addition to seeping out of the leather and staining your britches, excess oil can also soak into the leather too much, causing it to become "mushy." Over-oiled leather can stretch and become weak. Don't oil the underside of the stirrup fenders, as the rough leather will absorb too much oil quickly.