What Do Most First-Time Visitors to Berlin Get Wrong?

[Jonnythomsonss]

I'm visiting Berlin soon and want to avoid the usual tourist mistakes. While researching, I came across the idea of joining a Free Berlin Walking tour instead of planning everything on my own, but I'm curious if it's really the best way to get to know the city.

For those who've already been, what surprised you the most? Did a guided walk change your perspective on Berlin's history or neighborhoods? If you've tried different tour companies, I'd love to hear which one stood out and why. Any hidden tips or things you wish you'd known before your first day in Berlin?