#1 Remember to keep the root flare exposed
The root flare is at the base of the tree. It’s where the trunk flares out where it is connected to the roots. The tree breathes through root flare so be sure to keep it exposed when planting a tree or when moving dirt around the base of your existing trees.
#2 Don’t add too much weight (with soil or paving) over the root zone.
Most roots grow in the top couple of feet of soil. They will extend farther than the trees canopy. A tree takes up the majority of its nutrients from the roots along the drip line (the edge of the canopy).