Make a list. I find that when I write it down, see how things can mix and match, I pack lighter.
Travel in clothes that can be washed and worn while there. Add an extra layer, easily carry-able, so it's not in your suitcase.
Leave a little room for souvenirs - (I know that's hard) and make sure you know the costs of luggage when overweight before you travel.
If you pack a lot of clothes when traveling, maybe focus on one neutral color. Colorful tops... with grey and black bottoms or khaki and brown bottoms. This way, you will have less shoes, and most items will cross match.
Carry some small denomination bills... for tips and such when you travel.
Email and scan itinerary to a friend before leaving. Also leave a copy in a "cloud," so you can access it. Even a copy of your passport.
Have fun! Sounds so exciting!