I like tight proportions on my trees, but with mini-bonsai, aka mame, the challenge can be considerable. At less than 3″ in any dimension, for almost all trees you are pushing the limits of the size of the foliage or leaves.
A couple months ago, in late March, I cut all the new growth and some of the old growth off a 4-pack of Chinese Elm mini-bonsai. All of these trees were cuttings taken 18 months ago from overgrown but old branching on a larger bonsai, so they had some character to start with. I decided to cut all the new growth off because the proportions of the trees were simply too loose to make really good mame in the long term. Here is where we started in March 2020:
After another month of growth, the new shoots have hardened off and I decided to remove stubs that are from the last pruning, thin shoots and cut back and wire the desirable portions. Here is what they looked like before work, May 19th, 2020.
These are by no means show-ready, but with mame, as long as you can keep them from drying out and losing vigor in tiny pots, the amount of branching needed is so minimal that it doesn’t take long to develop.
Next, I’ll watch new shoots emerge and allow them to elongate while being sure to remove multiple shoots in any one area to avoid swelling. Since it’s getting warmer as summer approaches, I’ll sink the little pots half-way into larger containers with some pumice or bonsai soil underneath. I could bury them entirely, but this way I get to see the containers still. I’ll remove them every month or 2, trim long roots that have escaped and then replace them in the same spot to continue growing.
Good luck with your mini’s!