Biggest Newbie Mistake with RAW Footage?

Hey everyone, Chris here, working as a Key Grip. Been on a few sets recently where RAW was the primary capture format, we used an ALEXA Mini and some AMIRA bodies, mostly shooting with a Forza 500 II for key, and a couple of M18s for fills. My next personal project is shooting RAW for the first time on a short, just using my own R5 C, which has me a bit nervous.

I've been doing a lot of reading, and guides often mention things like underestimating GPU power for editing or not bothering with proxies. Those make sense to me. But I'm wondering, from folks who've been through it: What's the single most common and costly mistake newcomers make when diving into their first RAW project? I'm trying to preempt any major headaches down the line.