Raise your hand if you have a problem packing light. Ok, yeah, so... everybody ought to run down this brief un-packing list before their next trip. Your goal might be making more room in the suitcase, but the real advantage to learning to pack light is ensuring a stress-free journey every step of the way. Less stuff equals less weight to carry, fewer things to keep track of, and fewer choices to make when you get dressed in the morning.
Here are a handful of things you definitely don't need to pack:
A Third Pair of Shoes
Two will almost always do. A walking pair, and a dressier pair that you could wear to dinner. Anything else is just taking up room in your suitcase that you'll need for souvenirs.
A Second Pair of Jeans
Unless you're going abroad for a month or more (and even then, I think you can get away with it), just a single pair of durable denim will do 'ya.
No matter where you're headed, there's always a risk of losing your valuables due to theft or just clumsiness. Get yourself a cheap watch, if you need one, and pack inexpensive jewelry. I have a friend who replaces her wedding rings with a practically-disposable $20 cubic zirconia set when she goes abroad.
If you're the "always prepared" type, it's tempting to pack a raincoat for your desert vacation. But no, you don't need to. It's one thing to pack a hoodie for a chilly night, it's quite another to expect a blizzard in Miami in November.
Full Bottles of Anything
Save space in your kit and pack only as much moisturizer, shampoo or medication as you need. Transfer the smaller amounts into tiny travel bottles or screw-top containers.
Anything You Can Buy Cheaply at Your Destination
You don't want to subject yourself to gift shop prices, but if you know your destination has a pharmacy chain and a grocery store, you can feel confident packing lightly on toiletries.
Guidebooks and Language Dictionaries
It's 2016! Almost everything you need, you can find an app to replace.