The best time of year to plant young trees is actually in the fall. This helps your trees concentrate on their roots rather then leaves and fruit. But as green houses are selling trees, spring isn't a bad time either.
For Planting, your best tool is your local extension office. Believe me when I say, use them up! Not only can you find some great deals on trees, but you can take soil samples in to be tested for a small fee. Testing the soil in the area that you wish to plant in will tell you what you need to add, or subject from the dirt.
Next are your trees.
Find trees suitable for your climate. I saw someone purchase a citrus tree just because the local farm store had one out for sale. But unless this person has an arboretums, I don't see it surviving in our brutal cold weather. Maybe it was a GMO, and spliced to make it here. I don't know, it wasn't listed that I could see. Your local extension office will be able to tell you what trees thrive in your area, if you have any questions.
The next tool used is what ever was missing from the soil. As our top soil was stripped, we had a lot of "adding" to do. Most of it was in the form of compost. Mulch is another thing to have on hand.
Once trees and your add-ins are on hand, planting is your next step. We use a spade for ours.
One reason we use this and not a shovel is because we snap shovels, just like we snap those potato forks. We work in the add-ins to the loosened soil with that ever present Garden Claw. And depending on what the add-in is, we may wait a few days before planting.
Once the trees are in, we must use stakes and tape to keep our trees straight. Otherwise that old reliable Kansas wind will have our trees almost laying down. Hoses now come into play. We are in the process of turning a horse tank into a rain barrel. A water source is important.
Pruning shears and a field knife are also tools we use. Some trees require certain pruning to happen. Shaping the tree to keep them from going "wild" is said to improve the fruit quality. The field knife come in use when suckers begin to grow.
Companion planting your orchard is a good idea, this tool we will call the cover crop. I use clover seed for mine (as the bee hives are in my orchard) but there are other cover crops good for your orchard.
Lay out of the orchard is a good idea as well. Placement for your trees can help with pollination, even those trees that claim to be self pollinating can receive benefits from a companion.
We are prepared for a harvest. Bushel buckets, ladders, and netting. Hopefully next year looks like our apple picking adventure of last year.