Domestic airlines will not pay you for cash, electronics, jewelry, art or antiques lost, damaged, or stolen from your checked luggage. Put these things, and anything else of “irreplaceable value” in your carry-on bag instead.
Book everyone’s flights in one transaction to guarantee the tickets will be truly linked. This will generally gives everyone traveling on the reservation the same baggage allowances and makes securing seats near each other in the plane more likely. It also makes re-booking easier in case of a missed or oversold flight.
Reduce the likelihood of declined transactions overseas by notifying your credit card issuers of travel plans in advance.
Long travel day? Many European airports (and train stations) have clean public shower facilities. Ditto for airline lounges in the US.
Checking in online 24 hours before your flight reduces your chance of being bumped from an oversold flight (as departure time approaches, airlines are more likely to bump passengers who have yet to show up or check in).
Airlines’ liability for your lost checked bag is $3300 on domestic flights, $1131 on international. Your carry on luggage is the safest place for anything more valuable than that. Most carriers exclude claims for cameras, art, electronics and jewelry from this coverage also.