Europe, particularly southern Europe, is generally more dressy than North America and you will look and feel out of place if you are dressed too casually, especially in the evening. In Italy and Spain I never went out at night in pants. I would not pack hair appliances like curling irons or blow dryers. They are big, bulky, heavy and you need a bunch of different adapters as what will work in one part of Europe will not necessarily work in another country. I was jealous when I saw someone with a hairdryer, but I just put my hair up everyday and got over it because its just not practical.
Shoes are likely the toughest packing decision of all.
You need comfortable shoes, shoes that can go out to dinner or the bar, shoes that you can hike in, sandals for warm weather and the beach, and something dressy. However, shoes are the biggest and heaviest items you'll probably pack. If you can, bring only 2 pairs, but no more than 3. I started with 2, then bought another pair and had 3, but I eventually gave away the running shoes and returned home only with sandals. Someone told me not to pack anything white .