Luggage
Check-on size is 9 x 14 x 22
Carry-on Eagle Creek with wheels (Switchback Plus has zip-off daypack & turns into backpack) and smaller bag that fits over handle.
Small fold-up backpack or fanny pack (like my blue duffle) to bring home gifts.
Mesh pockets in luggage or separate small bags are great for clothing.
Small mesh pockets to organize things.
"1/2 Cube" for t-shirts & underwear
Compressable stuffsack for sleeping bag or bulky clothing like fleece.
Can I snap daypack on front of my pack? Does front have hook?
Use bright luggage tags so you can find luggage easily.
"Sidekick" purse converts to fanny pack (both at same time for security)
Moneybelt (or neck wallet like I have) for passport/money/vaccine card/int'l drivers licence.
Film-sheild bag for x-ray

Packing Methods

Packing for 3 weeks is the same as for 5 days
1) Rolling method (can put clothes inside newspaper bags
2) Envelope method (put clothes inside store-bought envelope luggage) holds up to 10 shirts and compacts them
Small bag/cube to hold underwear
3) bundle method. Good unless daily packing.

Clothes

Some skirts & pants have zip security pockets (inside or out)
Quick-dry, wrinkle resistant
ie: Central Asia:
1 or 2 pants
2 pr shorts (or 1 if inappropriate for culture)
1 skirt
1 dress (maybe)
2 quickdry t-shirts (1 black, 1 light)
1 long sleeve shirt
fleece jacket
rain jacket
5 pair underwear
3 pair socks
All terrain sandles (for water, showers, hiking)
Running/Walking shoes
ie: Europe
dual-weave shirts wick sweat, stay dry, dry quickly (cotton/nylon)
shirts: 1 light, 1 dark, maybe 1 bright/fun. All should coordinate.
1 button-down long sleeve with rollup sleeves and vents. Can be worn as jacket. Snaps are nice in case you lose button.
Broom skirt (packs nicely)
1 pair Neutral pants/bottom (Convertible pant/short nice)
1 dress (short black) Can wear t-shirt under/jacket over
quickdry long (walking) shorts
quickdry underwear
tights
Jacket with zipout arms & pockets (make vest)
Light, black gortex raincoat
"Smart wool?" socks - thin, dries quickly
black flats for Europe or when you may dress up
Rarely take hiking boots unless that's the purpose of trip.
Sarong/Sari (or piece of material). Can use as shawl, travel sheet, coverup, scarf, skirt; especially in 3rd world country.

Accessories

Small fancy scarf to dress up
Inexpensive necklace & earings that you don't mind loosing (cheap wedding band)
Bandana
Tilly hat or rollable straw

Toiletries

Toothbrush that holds toothpast in handle.
Biodegradable soap (that you can use for laundry and shampoo) [Anywater, Campsuds, Mt. Suds]
Hand sanitizer to use before you eat to avoid traveler's diarreah
Use small leakproof bottles
They make a very lightweight hairdryer now.
Shower in a bottle "Revival". If you can't take a shower.
"No Jet Lag" pills
Eye mask
Pack-towel. Can cut a small piece for washcloth. Dries quickly.

Other

Travel sheet for hostels
Bug spray for 3rd world countries: Permanon or Congo Spray. One you spray on your clothes in advance and lasts a few days.
Water purifier or tablets
World map or post cards or photos of family to show others where you live and a little about your life
Something to give away.
Clothesline for laundry (they make an elasticized one that you don't need pins for)
Flat rubbermaid sink stopper (many places don't have stoppers in sink to wash clothes)
Travel lock with cable to lock pack to train or other things if going to bathroom, in hostel, etc.
Flat water bottle (Platypus)
Phrase book
Small flashlight
book
game
Camera, film, batteries, lenses etc.
Umbrella

Etc Info:

Keep money in different places on body.
Smile, good attitude!