Well I’m hardly the right person to ask as everything I am doing I pulled from watching numerous YouTube videos from nurseries to farmers to folks like you and I.
If available buy on dwarfing or semi - dwarfing rootstock. That may or may not be possible wherever you are as the rootstock’s tolerance to your soil and climate comes first.
All the videos for stone fruit talk of open center forms. Removing all inward growing branches. This is important for me as I live in a hot and humid place so air flow is needed to help keep disease at bay. Other places like desert dry heat might want the more crowded form to shade the fruit. Next is limiting the overall height of the tree to a level you can tolerate access to, whether by reaching, a step ladder, or something larger.
When the tree is young you will get several lateral branches that will curve upwards and want to grow vertically. The first year in the ground I didn’t prune the growth as I wanted the tree to maximize the amount of energy it collected via leaves to store in the roots for the next year.
So the tree in my photo, now in it’s second year in my yard (so 4 years old), had put on 4-5 foot new branches the first summer. I cut back each of these to an outward facing bud in late winter about 2 feet up on each branch from the growth points last year . Already this second year in the ground these single branches I cut back have each produced 3-6 new shoots varying from 1 foot to 3+ feet long. For the Flavor Grenade Pluot I’m speaking of, it flowered on second year wood, so everything that is growing this year should set flower buds for next spring.
So as is obvious from my photo, I really hemmed myself in space wise, so I may need to occasionally remove whole branches to keep the tree in check. The second hardest thing a home fruit grower has to do is cut away future fruiting wood during pruning. The single hardest thing is thinning set fruit.
So I don’t have enough personal experience to get further along in the discussion of pruning than this, but search on YouTube for your fruit type and pruning, specifically backyard gardening or permiculture. After you watch a bunch you will see the similar talking points they have.
I didn’t mention wanting to encourage more horizontal scaffolding (branching) as for this one tree I don’t have much room.
Apricots naturally grow more horizontal branches so they will perhaps be a bit easier to train.
Now that I’ve found this great forum I’ll be posting on my projects over time… Hopefully they will be helpful to others as much as others posts have helped me.
Here is another photo of my side yard. In the foreground is a Katy Apricot. First year in the ground. As you can see it naturally sets more horizontal branches.
The middle tree is a Cot-n-Candy Aprium. 2nd year. Then the background is the Flavor Grenade Pluot.