First up: what to wear when you're traveling so that you look polished, but that will let you be out and about all day sightseeing, shopping, museum-hopping, eating, and generally wandering (one of my favorite things to do when I'm visiting a new place is to just walk through the different neighborhoods and get a feel for the city).
My main guidelines are comfortable flat shoes, lots of thin layers so you can adjust for indoor, outdoor, day, and evening temperatures, and a bag that's big enough to hold everything you need, but not so giant that it's a pain to lug around. This usually translates to lots of skinny jeans, blazers and jackets, cross-body bags (no hands needed!), shirtdresses, and flat sandals. A couple of fine examples: