What is something you did when you first started playing that ended up being a big mistake?

Maybe this will help some new players from repeating our mistakes...

I didn't really understand the whole legendary items thing at first. I knew they had special attributes but didn't understand the crafting process and didn't want to sell them yet until I figured out what build I was going to go with. I had maxed out my stash with a bunch of other regular crap so just held on to them and was lugging this large inventory of legendary weapons and armor around with me everywhere I went which eventually prevented me from being able to fast travel. I figured out you could drop stuff and retrieve it later so started hiding things around my camp in discrete locations. One day I got the great idea of dropping and hiding them in my shelter and yeah...a couple weeks of legendary hoarding gone.