Leather straps should be kept dry. Even if a strap is water resistant, exposure to moisture, especially with chemicals such as the chlorine found in pool water or ocean salt water can cause the strap to decay, become brittle, crackle and eventually break. To help extend the life of your strap, if it has been exposed to salty or chlorinated water, gently wipe it with a cloth, lightly dampened with clean water and let it air dry. Also, perfumes or hairspray should be avoided in order to preserve the finish of the leather. When you install a new watchband, we typically recommend wearing it 1-3 holes loose at first, then tightening it by one notch each time you wear it to allow the band to mold to the shape of your wrist. If you force it tight to your wrist too quickly, it can cause tearing and dramatically shorten the lifespan of your new strap.
Exotic leathers, such as crocodile, alligator, lizard, should follow the same precautions, especially since many have been given a glossy-looking finish which can crackle as it ages with rough care.