What was the most important lesson you learned from any fashion/style mistakes in 2016?

Mine was that if I buy clothes in-store, they are more likely to turn into orphan or neglected items than if I purchase online. I really need the luxury of time in deciding whether to keep an item, and I need to try it on at home. Keeping the item for a few days allows some of the excitement to wear off, and enables me to make a more informed decision.