Make two packing checks
First, check your operating airline’s size, weight and item limits for the fare you bought. Then consult the official security guidance for each airport where you expect screening, including connections and the return trip.
Look up uncertain items individually. TSA’s travel pages are a useful starting point for US screening; they are not a worldwide packing rule.
Check items that need special handling
Review the current instructions for liquids, electronic devices, batteries, medicines and any specialist equipment you carry. Check both the airline and screening authority where their requirements overlap.
Keep required supporting documents accessible. If an item is essential to your journey and the published guidance does not resolve your question, contact the airline or security authority before travelling.
Prepare for the checkpoint and a possible gate check
Organise your bag so you can reach documents and remove items if staff request it. Follow the instructions at your checkpoint: equipment and procedures can vary between airports.
If the airline asks to put your cabin bag in the hold, ask which items must be removed before handing it over. Keep your travel documents and permitted essentials with you, and retain the baggage receipt.
Policies and laws can change. Confirm urgent or booking-specific questions using the airline or regulator's official source.