If you don't want to get all complicated, this is what I do in Tennessee.
I buy Miracle Grow Moisture Control potting soil and work it into the hole of whatever I'm planting, plant the flower/bulb/schrub/tree, cover with your regular dirt, then add some more of the Miracle Grow on top, this holds in the moisture after you water. Then mulch if you use it. I usually throw and handful of Osmocote plant food on top, It's little balls. I lived in NH and the soil up there was very dark and rich then I moved down south to this clay and started doing this and everything grows great.
Jan