diet and DNA are your best bases for good feet. beyond that i don't know what others do but if you really want to, you might use a fine grade sand paper to take ONLY the surface dirt off evening out the appearance and then apply an oil of choice. sandpaper is good for taking off hoof polish after competitions, for sure. normally, a good stiff brush will do.
i caution the use of peanut oil specifically as, 'specially if you intend to show, others will be handling your horse's feet. people that are allergic to peanuts seem to be VERY allergic to them. so much so that simply handling a peanut oiled foot can cause them rapid, extreme and life-threatening adverse affects. vegetable oil would be safer tho not as easily absorbed. there are plenty of good hoof greases/oils/creams on the market that will produce a suitable lustre.