A leather belt does not need much. It needs the right small things, done rarely.
Rotate it
Leather needs time to dry out between wears. Wearing the same belt daily is the fastest way to crack it. Two belts in rotation last more than twice as long as one.
Roll, do not fold
Hang it or roll it loosely. A folded belt develops a permanent crease at the fold, and that crease is where it eventually splits.
Condition once or twice a year
A small amount of leather conditioner, worked in with a cloth and left to absorb, is enough. More often than that and you soften the leather past the point where it holds its shape.
If it gets wet
Let it dry at room temperature, away from radiators and direct sun. Forced heat is what makes leather go stiff and brittle.
