Check all items are intact, and have all their parts.
Please note that this might not cover extremes of weather, and is aimed at 1 person travelling on foot. Write up your the list when you pack and edit it to your own preferences after your trip.
Remember to tell someone where you are going.
Water bottles. On average a person needs 2.5litres of water a day, this varies on daily exertion.
Water purification tablets and milbank (filter) bag, or all-in-one system.
Rucksack, and rucksack liner bag (or bin bags) for waterproofing.
Tent: Inner tent (net and groundsheet), outer tent (flysheet), poles, pegs, guy lines. Possibly spare pegs and a repair kit.
Inflatable pillow, and mat or airbed.
Waterproof jacket and trousers.
Clothing: socks, underwear, thermals or base layers, t-shirts, trousers/shorts or skirts, jumpers or sweatshirts, scarf, hat, gloves.
Lighter or fire starting tool.
First aid kit.
Penknife and/or multitool.
Stove and fuel.
Mug, fork, spoon, pans.
Washing up liquid and cloth. (Biodegradeable).
Soap, shampoo. (Biodegradeable).
Toothbrush, toothpaste. (Biodegradeable).
Towel. Consider microfibre for small size and quick drying.
Mini sewing kit.
Map and/or notes.
String or twine.
Food bags or similar for waterproofing. Sealable or with wire twists.
Torch and batteries.
Glasses and case, or contact lenses and necessary equipment.
Medications, vitamins, minerals, and any other items for your personal health needs. Take more medication than you should need.
And of course the usual things you leave home with like wallet/purse, keys etc.
Camera, spare batteries, and memory card or film.
Sketch pad, pencils or painting equipment.
Shaver and batteries or razor and foam/oil.
Cigarettes, tobacco, rizlas, filters, lighters.
MP3 player, mobile phone, alarm clock, and batteries or charger.
Foldable or wire saw.
Bacteria killing spray or gel for hand hygiene.
Plates, bowls etc. (I just use the pan or lid).
Pump for airbed/pillow.
Wire coat hangers.
Mallet for tent pegs.
Trowel or foldable shovel.
Additional bushcraft tools like an axe.
Comb/brush, and any other personal hygiene or cosmetic products like chapstick and ladies things.