The most basic requirements are to make sure that you have the right site and the right soil.
The site should be one that provides some, not necessarily full, sunlight. It should also be one where the trees will not be overcrowded. Eight to twelve feet apart looks like a lot when planting smaller trees. But as the tree grows it's not much at all and soon it's crowding it's neighbor.
The other consideration is soil. All trees obviously need moisture, but few deal well with too much. You want soil that holds some moisture, but drains well so that it doesn't remain saturated. It's somewhat of a balancing act but fortunately the tolerances are fairly broad and, while you may not be able to use the variety you want, you can generally find a variety that will fit.
One soil factor, unique to our soil conditions, is that our trees are being grown on rather light sandy soil. They do not do well when planted in heavy clay soils. The lighter soil around the root ball (captured by the tree spade) becomes saturated because water cannot readily drain away through the clay. This creates a "bathtub" effect, and can cause root rot. On heavy clay soil either build a berm or mound so the trees can be planted above grade, or find a source for trees that have been dug from heavier soil.
Assuming you have properly selected your site and purchased your trees, how do you plant them?
Many people pre-dig the holes for ball and burlap trees so that after picking them up they can get them in the ground as soon as possible. Start by knowing the size of the basket (root ball) and be fairly precise on the depth of the hole, but liberal on the width. Generally, the heavier the soil the wider you want the hole so that the roots can spread laterally into looser soil.
Our ball and burlap trees come in three basket sizes.
It is a fairly common mistake to dig too deep of a hole. You want the top of the rootball to be about 2" above the surrounding grade. Say you dig the hole several inches too deep. You'll now have to fill it in to get the tree to the correct level. However, the loose soil under the rootball will settle over time because of the weight and thus the tree will wind up having been planted too low. Remember that most of the roots grow laterally only inches below grade. A tree planted too deep will not grow as well as the lateral roots have to contend with relatively more compacted soil.
Be sure to cut the rope away as it it girdling the tree and will interfere with trunk growth. Also pull back the burlap to avoid too much dampness against the base of the trunk.
Water the tree as necessary the first couple of years. Again, you want to keep the soil moist, but not continually saturated. The only way to really know is to dig down in and check the soil, if you can ball it up in your hand, it's probably too moist already. However, don't rely on your lawn sprinkling system to provide enough moisture. Check periodically and use a slowly dripping hose if necessary. Many people use the dirt from the hole to make a ring around the location to aid in watering. Remember that too much water can be just as harmful as not enough.
If you are having a truck mounted spade deliver and plant the tree, the truck will first visit your side and dig the hole (thus there will always be one extra trip). It will bring the dirt to the farm, drop it along side the tree, and then dig the tree. Upon return to your site, it will fit the tree into the hole and then lift the spade blades for an exact fit. This is why you cannot dig the hole yourself. Without the exact fit, the dirt would fall away from the roots exposing them to the drying effects of the air.
We recommend that you do not fertilize the first year as you want the tree to first re-establish itself, not stimulate additional growth.
If a deciduous tree, prune only during the winter or in early spring well before the buds begin to swell.
If a conifer tree, prune in mid-summer. Cut only the new growth (which will be a lighter green and still soft). New buds do not sprout from old growth. If a spruce or fir, make sure to leave several buds behind. If a pine, leave at least 3"-4" of new growth and new buds will form at the tip.
We strongly recommend that, as conifers grow, if any branches extend to the ground, they should be removed so that there is at least 12" of space between the ground and the end of the branch. This will allow air to circulate underneath, and eliminate the continuous moist conditions that promote fungus growth.