To avoid losing crystals and studs....
Make sure embellishments such as crystals or studs are secured in one of the following fashions:

1. Onto a piece of hide that is then stitched onto leather, thereby hiding the back of embellishments.
2. Directly onto leather... but ONLY if the feet of rimsets ("prongs") can be seen on the back side of leather. If you cannot see the feet folded over on the back side of leather, crystals or studs will work their way loose and fall out over time. You should not be able to remove embellishments using your fingernail!!
To ensure hair or leather doesn't lift, gap, or shift....
Hair and leather should be securely stitched onto tack or leatherwork. This step takes a bit more time, but creates a more finished and durable product.
To avoid crystals breaking, fading, and clouding...
Purchase products that use only Swarovski crystals. These crystals have the highest lead content, which makes them the strongest, while being guaranteed not to fade or "cloud" like cheaper crystals.
To clean hair on hide...
Brush off loose dirt using a stiff brush. Use a damp rag to then wipe clean. Can also be hand washed using mild soap if tough stains remain.
To clean crystal tack...
Brush off loose dirt using a stiff brush (toothbrushes work great!) then wipe clean with damp cloth.
To clean leather...
Remove dirt and horse sweat using a stiff brush or damp cloth. Use a "non-darkening" leather conditioner to ensure your leather does not change color after it dries. Apply conditioner liberally and allow it to soak in for several minutes, then wipe off excess. Frequent conditioning will keep leather strong and pliable and prevent it from cracking with heavy use.