Don't be a Pack Rat
People often suggest bringing things-a favorite pillow or candles-to personalize your hotel room and make yourself feel cozy, but I'm a minimalist. Try not to carry your entire home with you; otherwise, you might as well just stay there.
For up to a week, I bring two cute outfits-a little black dress and a nice pair of jeans, maybe a jean jacket (which you can wear with the black dress). They all adapt nicely to dressy or casual situations.
I also stuff in a great purse, shoes that go with both outfits, and a wrap that can be worn with anything.
For makeup, I forgo all the colors and steps and just pack a little bag with bare necessities: gloss, lipstick, concealer, sunscreen, and mascara.
Don't forget those adapters for international outlets!
I love to anticipate serendipity, so I leave room in my suitcase for new purchases...or I pack an empty bag or knapsack. (If I buy a lot of clothes and there's no room in my bag, I just wear lots of layers on the flight back.) The combo of suitcase-bursting-at-seams and stern-looking-suspicious-customs-officer makes for an unpleasant reentry.