A. prevent others from making the same mistakes
and
B. make myself feel better about my own stupid mistakes

My biggest most recent whoopsie came when I was trying to gently clean up the back of a cel that had paper stuck to it. I had the cel on a smooth surface and made every effort not to move the cel around much but the cel was old and had raised areas from previous manhandling. When I was done removing the paper, I flipped the cel around and noticed that these raised areas were now a bit scuffed from contacting the surface I was working on. I was a huge dummy and should have probably at least had the cel on top of a cel bag or something (would a towel have been better? I don't even know anymore...) Lesson learned, cel surfaces are more susceptible to scuffing than I had realized. I just am thankful it wasn't a huge wishlist shot or an A1end or something T^T
So any other horror stories? Hard learned lessons? Just no shaming, cuz I'm sure we already feel bad T^T (whhhhhy, whhhhy did I have to work on removing that paper...)