1. Keep roots moist but not soaked, and plant as soon as possible.  Unwrap and soak your tree/shrub in a bucket of water for an hour or two before planting.  Prune away damaged or dead roots.  Dig a hole while soaking.
  2. Pick a good spot with the site characteristics you need (sun/shade, wet-dry, loam/clay) and consider the dimensions of the grown plant (i.e., do not plant a tree that gets to 80 ft under a powerline).  Dig a hole that is about 2X the size of the root ball, set soil to one side.
  3. Add soil amendments (compost and peat) and mix with native soil.  Maple and lilac benefit from lime amendments.  Make a small soil mound in the bottom of the hole and spread the roots out over the mound.  You want the roots to spread as they grow.  Check that the plant will be at the right depth.  Grafts need to be 2-3 in. above the final soil line.  Try to determine what the original soil line was and replicate that.  Fill in the hole while keeping the tree vertical (you want it to grow straight up).  Pack the soil by hand as you fill the hole.
  4. Gently tamp down soil with your foot.  Use some soil to make a small berm around the tree/shrub to facilitate watering.  This is especially critical if planting on a slope.
  5. Water well, tamp down again gently by foot (this gets all the air out of the soil and keeps the roots wet).
  6. For bigger plants, you might want to stake it in place against the wind, rain, and pets.  Use 3 stakes to keep plants upright.
  7. Some plants are especially vulnerable to wood borers, including fruit trees, crabapples, flowering cherry, etc.  These trees will have to be protected by special paper wrapping.  Without it, mortality can be close to 100%.  Wrapping is also effective against rodents and rabbits who eat the bark of young trees.  Don’t bother planting hardwoods near beaver ponds.