Use sand socks for camp shoes. They weigh nothing, can ball up into a tiny pack space, have enough tread to protect your feet, and cost $9 on Amazon.
If you're backpacking with a group, someone should bite the bullet and bring a 6x8 or larger "community tarp." It's nice to have a dry spot for the group to hang out if it's rainy.
Wear lightweight gaiters and soak them in permethrin. Keeps the crap out of your shoes and ticks off of you. Dirt cheap on Amazon.
Always use a lid and wind guard when boiling water, even if it's just heavy tin foil. Those 2 items make the biggest difference in stove efficiency.
Attach a small carabiner to your bear bag line, and tie a small loop in both ends of the line. Clip one end to your belt loop when you're tossing your line over a branch. No chance of it getting hung up out of your reach, and you can just clip the loops together when it's not in use so it can't fall out of the tree.
Carry something to sit on, like a square of plastic or old foam pad.
Put a stripe of bright paint on small, neutral colored items (sporks, cups, knives, binoc cases, etc.). They have a tendency to vanish when they hit the ground otherwise.
It's easy to rig up a gravity-feed water filtration system that can feed back directly into your camelbak's drinking tube. Sawyer mini, evernew bag, a bit of hose, and an adapter kit from camelbak. You can refill your bag without taking it out of your pack.