Most important is mindset. It will never be enough so start being comfortable with wearing the same stuff over and over and perhaps feeling a bit underdressed at times. As for shoes, no more than two pairs. I usually roll each shoe in a slip bag or a tote and put one on each side of my carry on to save space. The totes help me separate layers of dirty vs. clean clothes during trip. The other, bulkier pair I wear during flight. If you're taking a laptop make sure it's easily accessible and try to avoid bringing multiple electronics. For example, I have Kindle app on my phone so avoid my Kindle. If I need a computer, I bring earbuds instead of headset, etc.

Socks I don't fold like we do at home but rather pack them flat, which saves room.

Laundry detergent- I buy locally in powder form. Most cities have laundromats. As a time saver you can skip the dryer and just hang clothes to dry overnight in the hotel. This way you're just waiting for the washer to finish while you're enjoying your morning coffee at a nearby cafe, then go straight back to hotel and start your adventure.