DO.
NOT.
SOFTEN.
I use compressed air to blow off the lint from the inside of holsters, wipe down holsters and belts with the least damp cloth possible (as in dampen and wring out one cloth, and then wring it with a dry cloth)
After that, I use Obenauf Heavy Duty Leather Preservative
http://thebeltman.net/preserve.htm
I haven't found a better price per ounce than BeltMan, the free shipping means it beats pretty much anywhere else I looked, and I did go looking when I got a jar for my F.I.L.
I like the Obenauf product, it goes on easily, smells good,
works, protects the leather, and cleans off of me without fuss. It also doesn't smear on clothing, I've never bothered to put stuff I use Obenauf LP out of service, I just use it the next day as normal.
I use it on belts, holster leather, boots, and even my wallet - great stuff, and cheap, too! I might be 1/3 of the way through the jar I got at least 2 summers ago (so at least 18 months) and I really slather it on liberally.