Clay soil varies across the country, and the parent rock from which it derived gives each clay particular qualities. My calcareous clay of central Texas is well-drained for a clay. It is slick and sticky when wet, but becomes hard and clods when it's dry.

The main problem with clay is its density. Never bury the root collar of trees or shrubs. In clay soil, especially, this can lead to fungal disease. In fact, never pile mulch up against this area. When planting only dig as deep as needed to keep the root collar above the soil level. You can dig the hole as wide as you want, and I think it important to spread the roots of transplants before filling in the soil.

I also think it is important to add compost to the top layer of soil. That's because my soil, though mineral rich, requires humus to unlock nutrients. Your soil may not have this issue, so check with your local county extension agent. Nonetheless, I don't see how adding compost is ever a bad thing.

Thank you so much for the insight! I just planted my first ball/burlap Nellie Hollie today, that’s probably the last time we plant something that big by ourselves but I was so glad to have your advice today!
If anyone has proven shrub variety /landscape tips for all this clay I’m all ears!