mary, here is my advice for packing.
1. pack as much black, and things that match black, as you can. if you are wearing things more than once, black stays the cleanest and always looks polished.
2. don't bring too many pairs of shoes. each pair should have a function, and you should wear them at least twice. shoes are heavy and take up space. don't bring extras.
3. only pack for 2/3 of the number of days you are going. of course, bring enough clean underwear and socks for everyday, but be prepared to wear at least 1/3 of what you bring twice.
4. don't bring more than two items that serve the same purpose. for example, say you have a black cardigan and a black blazer and a black sweater. you don't need all three.