Extra clothes:
Don't bring more than you need, but make sure you're warm.
For example, I carry only one pair of underwear, running shorts, and extra socks
(besides jacket and long johns).
Ask why you need extra pants or shorts and how you could do without.
If my pants get wet in rain I wear the long johns and shorts.
For hiking in many areas long pants are needed due to cactus or snow.
No cotton.
Rain protection:
Desert rains can be heavy. In mountains it will rain even in summer.
Sun protection:
Watch glare from rocks or snow. Hat, chapstick, sunscreen, sunglasses.
Food & drink:
Extra food - can't buy it on the trail.
Water:
Locally and in desert you have to carry all water,
in some mountains it is often available but must be treated.
Illumination:
Map and compass:
On many trips, especially in desert, there is no trail where you want to go.
Second & First Class requirements.
Flashlight: We won't have camp lanterns on the trail.
Matches and fire starter
Hardware:
Pocket knife
First aid kit - comb to remove cholla. Snake bite kit?
Your medicines (Benadryl, inhaler, Tylenol, antidiarrhea).
Tent
The person carrying tent should have tent buddy carry equal amount of group weight.
Sleeping bag
Ground cloth and pad - watch weight
Closet:
See extra clothes above. Boots. Two layers of socks (not cotton).
Bathroom:
TP, small towel, comb, toothbrush, soap, bug juice, personal hygiene, etc.
Kitchen:
Stove
Small 1-burner propane/butane stove. Share stove & food?
Pots and pans and utensils:
Take only what is needed for meals planned.
Try to bring pots with multiple uses.
Watch weight. No cast iron!
If little water clean with sand to remove food (not on Teflon or cast iron),
then rinse with a few drops of water .
Some use aluminum pie tins for cooking so you don't have to clean them,
but pack out trash.
I take only 2-quart pot with lifter,
2 small cups (1 to eat from), and a spoon.
Food:
Plan one-pot meals that don't need a lot of time or clean up.
Remember you have to carry fuel and water to cook and clean.
For short backpacks some cans are OK if you carry them out.
For example, ramen noodles with canned chicken, Lipton noodles with tuna.
Get more ideas.
Trash bags (plastic) - Bring several:
for trash, covering your pack from rain, dirty clothes, etc.
Extras:
Remember you have to carry it. Think small and lightweight.