Before the trip

• Print a hardcopy of addresses of the most important people in your life, and all places you'll be staying on the trip. A hardcopy is more likely to survive and be usable in an emergency than a digital one.
• Print your schedule. Not just flights, but all transportation. Also meetings, etc.
• Notify family, friends of flight times and flight numbers.
• Check tipping practices at the destinations.
• Get some cash for the destination.
• Do an online checkin for the flights, if possible.
• Print e-tickets and boarding passes.
• Pack.
• Clean up at home. It reduces stress considerably to come back to a clean home.

On the trip

• Buy presents for partner, friends, family.

After the trip

• Review this checklist, and update it as necessary.

Packing

This is a master packing checklist, not something that must be taken on every trip. On the other hand, I've travelled according to this list for trips of several weeks, and it all fits into a carry-on suitcase of maximum dimensions.

• papers:
  • this checklist (for packing for return trip)
  • print-outs of e-ticket, boarding pass
  • passport
  • copy of passport on paper
  • prescriptions for medicines, if any
  • map of destination, if applicable
• electronics:
  • laptop
  • laptop power
  • laptop power cord for destination
  • gsm phone
  • USB cable for phone (for charging at least)
  • USB hard disk
  • USB hard disk cable
  • USB stick, with encryption keys
  • USB stick, for swapping data with others
  • USB stick, for re-installing laptop from scratch
  • earphones
  • power plug converter
  • power strip
  • 3+ m ethernet cable
• photography:
  • camera body
  • 50 mm lens
  • camera charger
  • memory card reader
• hygiene:
  • toothbrush
  • toothpaste
• clothes (packed or worn):
  • 5 pairs of socks
  • 3 pairs of underpants
  • 1 pair of longjohns
  • 1 pair of trousers
  • 1 belt
  • 3 t-shirts
  • 2 shirts
  • 1 sweater
  • 1 jacket
  • 1 pair shoes
  • 1 pair gloves
  • 1 hat
  • 1 muffler/scarf
• misc:
  • home keys
  • watch
  • little toy frog
  • sunglasses in case
  • wallet
    • euros
    • cash for destination
    • credit card(s)
  • money belt
    • reserve credit card
    • travel insurance cards (Pohjola, Tapiola)
  • medication
  • microfiber cloth for wiping glasses
  • notebook and pen
  • business cards
  • laundry detergent (unless bought at destination)
  • book for entertainment
  • nail clippers
  • carry-on suitcase
  • plastic or other bag to hold dirty laundry
  • blister plasters