Excellent.
For you elm, just prune enough to keep the general shape for the rest of the year. Begin to think about what you will do with it over winter. When reading different posts, PAY ATTENTION TO THE LOCATION OF THE POSTER. Ignore advice from folks more than a hundred miles from your climate zone. In other words, don't trust my wintering advice, I don't know your climate will enough. You have a few months to make your plan, and it can be simple and easy. Don't opt for the most complicated scheme.
Second, if you feel hooked, and find yourself wanting to do more, you need to pick up more trees. Most need something more than 10 to 25 trees, so that they will always have something to do. The "letting it grow" can try ones patience. More trees, more "bonsai stuff" to do. More trees die from being over worked without recovery time than anything else. So buy more trees.
Indoors, you can't beat ficus. Most of the ficus species are great for indoors bonsai. Remember a pane of glass cuts 30% to 60% of incoming sunlight, best indoor bonsai are tropical trees listed as part shade or shade lovers. Read through the Tropical sub forum to get an idea of the wide range of trees available.
Third. Get to a bonsai show. The autumn show season is coming, make a day trip to a local show. Looking at exhibit quality trees is very educational. And join a local club if possible.