I like to use Leather New made by Farnam. It seems to work good. I only do our saddles about twice a year and our saddles get used pretty hard. I will take a vacuum cleaner and suck all of the dirt off and out of the cracks, wipe it down with a rag, then use the Leather New with a damp rag (or toothbrush if it is tooled) and scrub on it. Let it dry and then buff with a soft, dry clean rag. I do all the undersides of the skirts, fenders undo the stirrup leathers to get all of it.
I have also used Murpheys Oil Soap with a little water and a sponge or Olive Oil. But most of that stuff will darken leather.
I have been told not to use Neatsfoot Oil Compound because it will break down leather.
There is probably better ways, but I have been getting by with doing it this way.
I DON'T LEAD 'EM AND FEED 'EM, I RIDE 'EM AND SLIDE 'EM.