Have you grown any ornamental cherries before? Let me just say..........they have issues, some more than others :-) In my area, Prunus subhirtella 'Autumnalis' has more than most. The late season bloom period is very sparse, usually producing 10% or less of the more typical spring bloom, so the 'autumn' part of the tree's appeal is underwhelming at best. It is also prone to the same host of disease and insect issues other flowering cherries are. Most trees in my neighborhood appear more dead than alive as a result. YMMV

As to how to prepare for planting and how to plant, your local Tennessee Arboretum has an excellent planting guide. I'd suggest you read it carefully and follow it explicitly for best results. Planting a Tree or Shrub