Cabin bag checklist
What to take in the cabin: documents, medication, devices and power bank, a change of clothes and in-flight essentials, plus liquids, sharp items and size checks.

[ ] Check your own fare's rules on the airline's site
    Size, weight and the number of pieces differ between airlines and even between fares of the same one. Check your ticket, not a general rule.
[ ] Put documents and money in the cabin bag
    Passport, boarding pass, insurance, cards and some cash. None of it belongs in the hold.
[ ] Carry the medication you take in the cabin
    In their original packaging and with a margin for delays. If you have a prescription, bring a copy: it simplifies questions on the way.
[ ] Move the power bank and spare batteries to the cabin
    Lithium batteries are normally not accepted in the hold. Capacity limits vary by airline — check yours.
[ ] Put devices and chargers in one pouch
    Laptop, tablet, headphones, cables, adapter. Security often asks for devices separately — easier when they are together.
[ ] Pack liquids according to cabin rules
    Small containers in a transparent bag. Medication and baby food are usually an exception, declared separately.
[ ] Check the bag for sharp and prohibited items
    Nail scissors, a multitool, a corkscrew, a penknife — the things that live in a bag for years and surface at security.
[ ] Pack a change of underwear and a t-shirt
    This is your insurance if the luggage is late. One change weighs almost nothing and makes a real difference.
[ ] Take something warm into the cabin
    Cabins are almost always cooler than they feel at boarding. A sweater or scarf beats a blanket and is always to hand.
[ ] Keep keys and spare glasses out of the hold
    House and car keys, glasses, lenses and solution. None of it can be replaced quickly in another country.
[ ] Carry valuables and fragile items in the cabin
    Jewellery, devices, device paperwork. Carriers' liability for such items in the hold is usually limited.
[ ] Pack a child's kit in a separate, reachable pocket
    Snacks, water, wipes, a change of clothes, a familiar toy and something for their hands. Everything must come out with one hand.
[ ] Take what makes the flight bearable
    Headphones, an eye mask, water bought after security, lip balm, gum or sweets. Small things decide a long flight.
[ ] Get everything ready for working on the way
    Laptop charged, files downloaded, offline access checked. There may be no internet on board, or it may be slow.
[ ] Save offline copies of your documents
    Scans of passport, insurance, bookings and tickets on your phone and in the cloud. A lost document is replaced faster that way.
[ ] Weigh the bag and check it against the size frame
    At home it takes two minutes; at the desk it is a queue and a surcharge. Check both the weight and that the bag fits the frame on every side.
[ ] Put in-flight essentials in the top pocket
    Documents, headphones, charger, water, medication. So you are not pulling the bag down once everyone is seated.

Checklist from Unload: https://unloads.me/c/carry-on-bag