You need to know the options. Which ever you do, have a complete report done, it is most times cheaper to do everything than to do one or two elements. Work your soil the least possible. If you have to dig a ditch you are 'cutting' the mycorrhizal grid. Cut your ditch so as to leave connecting areas between existing plants.
Some plants care about their soil.
Some do not. Ceanothus hearstiorum grows well on clay but hates sand. I've tried it in Cambria in sand and had it fail. This is only about 10 miles away from its native clay. Most of our plants do not care as long as they are with their associated plant community.