Answer: The part that doesn't get much sun will probably continue to be a bit thin, no matter what you do. In order to make a plant bushier, plan on doing some pruning periodically throughout the year, especially in the spring and summer. You may find that it is difficult to get and maintain the round shape, but it is worth a try.
You can prune the plant to whatever form you desire. Keep in mind that it will want to grow more toward the bright side. The more "artificial" you make it look (like a French Poodle!) the more work you will have in keeping it looking like you want. Use sharp, clean pruners and don't bother to paint the pruning wounds. It is not necessary, especially for a ficus in your area.
Enjoy your new plant!
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