expression, godan verb (-ru)
start with the outward form; focus on appearances first; get the trappings right before substance
Often implies a criticism that someone is prioritizing superficial aspects over essence or content. Can be used neutrally when form is a practical first step.
彼は語学を学ぶとき、いつも形から入る。まず高価な教材を揃えるんだ。
When he learns a language, he always starts with the looks—first he buys expensive study materials.
趣味を始めるときに形から入るのも悪くない。道具を揃えるとやる気が出る。
Starting a hobby by getting the gear right isn't bad either; having the tools motivates you.