Another thing I do is roughly plan out my outfits. In other words, I make sure the shirts I bring match the jeans, etc. I also never change for dinner, unless something happened that day (like got soaked in rain, or spilled something). While I find Europeans dress a bit nicer than Americans on the whole, it is not that they do not wear jeans or similar clothing. It is more the cut and style. For example, I do not wear graphic t-shirts ever here or there and I tend to wear leather shoes, not running shoes. If I do wear tennis shoes, I tend to wear lower profile, "retro" gym shoes.
I also check the weather right up until we leave to make sure I am bringing the correct types of outfits in general.
For example, we went to France in mid-October. I was originally expected it to pretty much be fall weather (highs in the upper 50;s, lows in the mid 40s). However, when I started to monitor weather in the cities we would be in, I noticed a serious warming trend. Some days were predicted to have highs in the low 70's. Because of this, I altered the number of sweaters I packed and instead leaned toward long sleeves and a few three-quarter length tops, knowing I could layer with a light jacket or fleece for morning and evening.
I love packing cubes. I buy mine on ebags. I can generally fit 12-13 knit tops in one medium cube for reference.
I get where you are coming from with over-packing. While I am not a fashionata, I do like looking nice and having choices. 14 days of black pants with 7 solid color tops and one pair of shoes is not MY idea of vacation.
