If you ride a lot, your leather is going to get dirty. Sweat, mud from the trail, dust from the arena footing, and dirt from your hands all get rubbed onto tack. You should wipe it off with a damp rag after every ride and plan to do a thorough cleaning occasionally to keep things supple. Exactly how often you do this depends on how many hours a week you are in the saddle.
Synthetic tack is easy to hose off with water and wipe down. It requires little maintenance other than regular inspection for wear and tear. To clean leather, you will need a good sponge, warm water, some saddle soap (or your favorite leather cleaning product), and a bottle of leather conditioner.
Take apart the bridle and unbuckle any pieces that buckle on and off so that you can get to every little nook and cranny where dirt loves to hide and grind at the leather. Wash everything down with the warm water and the sponge, opening up the pores of the leather. Use some elbow grease to remove any surface dirt.
Cleaning your tack regularly gives you a chance to inspect it for wear. Immediately repair or replace anything that is about to break, and keep a close eye on anything that looks well worn. Good quality horse tack is made to hold up to the job it is made to do, but keeping it clean will help it hold up that much longer.
Rinse off, get some clean warm water, dab some leather cleaner onto the sponge, and lather up your leather. Rinse it off and let it dry some. Before it is completely dry, work in some leather conditioner. Some leather conditioners may darken light leather, so test a hidden area first before doing the entire piece.
Keep your leather tack — saddles, bridles, and leather halters — in a cool, dry place. Dampness will cause mold to form on the leather, and too much heat and sun exposure will dry it out.