What are the biggest mistakes people make when warming up Reddit accounts?

My biggest mistake from personal experience is posting instantly after account creation. Wait a bit.
Also, DON'T start right away at nsfw.

Biggest mistakes are posting too aggressively, joining spammy subs too fast, low-effort comments, and repeating the same content everywhere. In my experience, natural commenting helps more than posting at first. I usually warm accounts up for at least 1–2 weeks with normal activity before doing anything serious