Boxwood can be one of my favorite trees to work on. I enjoy the leaves, bark and trucks. They are also a tree I caution students on because of the amount of work they can take. I only collect and work on one of these in my own collection. I would never have more than that. Folks with many of these have to have the patience of a saint to work them well.
First, there is the vision of how you want to style them. My personal preference to to style them like an Oak. That means selective branches all wired and moving like an oak here in California. I let the tree blow out and get very full. This will cause the tree to loose growth internally so I have to watch it carefully. If the the tree gets too dense, it will not have healthy ramified branches.
Second, how to achieve that look. I tell my students that they need to remove every other leaf of the boxwood at least once a year. I do mine several times a year because I am aiming for the twigginess I prefer. I sit down in front of the tree and my mind goes into meditation mode. I do not count leaves. My mind and hands run down EVERY single branch and doing the defoliation. Not a complete one because if you took all the leaves off branches would die. I work the tree until is it done. Zoning out and letting fingers do there job is the best way. For those who are afraid of the process it can be daunting. You just have to give that up and settle in for the long run.
After the partial defoliation is done, I go back through every single branch. This must be done. You bonsai is not a hedge. Every branch that will be left on the tree will be WIRED. So branch selection is done. Bring branches back into the profile is done. The seasonal blowout has thickened branches. and made them stronger so I but back to buds and start all over again. This will create ramification but it will take years to complete. Next step is to wire. That process is another labor of love and I will wire like I worked the leaves. Settle into, put on some Max Ricther minimalist music and wire away.
After cut back and branch selection and before wiring. The tree is open and can now be styled. A few more branches will be removed along the way to reveal more of the dramatic trunk.
Also want to share some pictures from a recent Shohin show I participated in. This one in Oakland, CA. The tropical trees are mine: