Here is a checklist of the essentials that indianbackpacker.com would recommend you to carry for your next trip. You may take a printout of the list, to assist yourself while backpacking.
THE BASICS
Backpack (3,000 to 5,000 cubic inches)
Sleeping bag (rated to 20 to 50F)
Sleeping pad
Two-person tent/tarp
EATING AND DRINKING
2 one-liter water bottles
Water purification (filter, iodine, or bleach)
Waterproof matches and lighter
Cup or mug
Lightweight bowl and spoon
Multi-tool or utility knife
CLOTHING
Trail-Running shoes or hiking boots (broken in and waterproofed)
Sandals and fleece socks or lightweight camp shoes
Wool socks
Sock liners*
Compared to other vacations, backpacking can have serious side effect for people carrying just a little less or maybe just some extra stuff. This list is focused on a three-season, three- to five-day outing, but when packing always plan against the highest high and the lowest low temperatures you'll encounter a few changes.
Try dividing your stuff into different compartments. Keep all your food in one place and your clothes in the other. This helps save time as well as keeps it more organized.
Synthetic long-underwear bottoms and tops
Synthetic shorts or convertible pants
Underwear
Synthetic/wicking t-shirt
Rain/wind jacket and pants
Wool or fleece jacket or vest (if warmer)
Wool/fleece gloves or mittens*
Bandanna
ACCESSORIES
Directions, trail map, or guidebook
Headlamp
Toilet paper in Ziploc bag
Plastic potty trowel
Extra Ziploc/trash bags
Lip balm
Sunscreen
Hand sanitizer
Toothbrush and toothpaste
First-aid kit (Band-Aids/bandages, Aspirin, antiseptic
wipes, poison ivy treatment such as CORTAID®
Treatment Kit, moleskin, tweezers)
Pack rain cover or garbage bag
*Indicates optional/depending on climate and geography
OPTIONAL ITEMS
Trekking poles
Sun/rain hat
Sunglasses
Journal & pen
Camera, film, charger
Ground cloth
Duct tape
Watch
Whistle
Small Strainer (for filtering food particles while cleaning dishes)
SPECIAL CONSIDERATIONS
Women: bring a few tampons even if you aren't expecting to need them; backpacking can do weird things to your cycle.
Contact lens wearers: bring solution and back-up glasses