When I got my very first Brooks saddle I made the mistake of treating it liberally with neatsfoot oil (top and bottom) so it would break in quickly. Don't do that! Not only did I significantly shorten the life of the saddle, but it never stopped significantly staining clothes.
On saddles I owned after that, I started treating the bottom only of a well heated saddle with SnoSeal. This has been successful in a (not too) conditioned saddle with good weather protection and no staining. I should mention that there are a million different ideas on how to prep a saddle for a long life.