How do I get better at interviews

I'm interviewing a lot of people lately, in the 3 months, my company hired over 40 people and I conduct them alongside my manager. The goal is to grow fast but I keep coming up with the same problems - many of these interviews are not in my technical domain and my manager usually has only a broad understanding. How can I get better at identifying good candidates for roles in which are not linked to my day-to-day (I work as a mechanical engineer).