I assume you're asking about safety gear and not clothes, shoes, etc. Better already right at the start
...given the question I assume you're not exactly at home in the vertical, probably more on secured paths.
Definitely, helmet first. Let all laugh and sneer to themselves, but we must change that thinking. A few years ago cyclists didn't have them either, today you're the biggest fool on the road if you don't have it on your head. Then I recommend a climbing harness and belay kit. I could say take two prusiks and two slings, but I can't. Better a few € more and buy a ready-made kit with belay plate. Don't buy new "fancy schmancy" kits with some hidden protections on webbing - once you fly, you can throw such a kit in the trash. Via ferrata gloves seem useless to me. True, my hands are hardened from rock, but still - cables are for belaying, not for pulling, climb on rock.