Key is to regularly water newly-planted plants, at least bimonthly for two months. It is also important to ensure you choose a location where your plant has enough space, which you can calculate from a variety's eventual height and spread.
Dig a hole twice the radius of the rootball. Before planting, drench the rootball. Place the pot in the hole, ensuring it sits no lower than an inch below ground.
Fill the hole with a mix of compost and garden soil, and add fertiliser and mycorrhizal fungi. Do not compress the soil. Give your plant a good watering. Add mulch on top whether bark and wood chippings, compost, manure, leaf-mould and stones. Make sure mulch doesn't touch the stem.
Apply fertiliser and replace decomposed mulch come spring.