The most effective way I have seen steps installed in terms of settlement is where the poured foundations have perches incorporated in them, and the perches support the steps.
Anything else, other than digging down to solid virgin ground, is a shot in the dark.
"It's You vs. You"
"People Throw Rocks At Things That Shine"
My Equipment Brag List:
-1 CAT hat
-16 pairs of Hanes socks (the Heavy Duty model), many with holes.
-12 pairs of underwear, ranging from Joe Boxers to Jockey, many are in need of replacement. (no more photo requests please)
-hundreds of t-shirts. Some w/ grease stains, some torn & tattered.
-7 pairs of jeans, ranging from Levis to Polo to GAP. 1/2 of them have holes in 'em.
-1 pair of old worn out Nike shoes.