The best travel advice I ever received was to pack LIGHT! Having traveled with a single carry on- I can confirm that you don’t need to pack as much as you think.
1. YOU CAN ALWAYS WASH IT There are laundry facilities everywhere! For a small fee you can either pay someone to do it for you, or do it yourself.
2. IT WILL ALWAYS GO When you have to be careful about what items you pick chances are you will decide on staple pieces that you love. That way you'll get wear out of every item you bring.
3. YOU CAN ALWAYS BUY IT Remember: whatever you forget (or want) you can buy abroad! Plus, it will likely be cheaper.
4. CHEAPER If you pack light enough, you will likely avoid costly baggage fees.
5. LIGHTER No one wants to get lost, or stuck walking with a heavy bag for a long time. But, this won’t be a worry if you pack light.
6. PEACE OF MIND Packing light promotes a minimalistic lifestyle. You’ll realize what you actually need to survive opposed to what you want.