When I plant, I like to dig a trowel hole just big enough for the root ball. I put the seedlings into the hole and then go along the row 'puddling' in the plants. This means that I fill the hole with water - well I use dilute comfrey liquid. This washes soil into the hole and begins to cover the roots. You have to be careful not to wash the plants out of the hole. I hate to see my brassicas keeling over after I have planted them and doing it this way means that they stay upright and healthy.
Finally, I will go along the row scraping the soil back into the hole with the trowel.
After planting I cover the seedlings with plastic netting to keep the pigeons off the plants.