Many thanks for all these helpful replies. I also asked the question of some colleagues, and got the following responses:

"I have a simple philosophy. Fill what's empty. Empty what's full. And scratch where it itches." Alice Roosevelt. Works for flying.

Switch to local time as soon as you take off.

Don’t exchange currency at the airport, get it in advance or use an ATM.

Fly non-stop whenever it’s possible

Don’t choose Row 1. Bulkhead and no overhead storage (lockers used by crew and full of mags, safety demo equipment).

You’re never off-duty on a business trip, even in the bar. Keep it professional.

Plan your arrival and first appointment (at least), and work back from there. Stopover on flight, plus oh-sh*t-double-oh landing time plus no public transport plus lousy hotel room equals a really bad state for that vital business meeting, being held at an address which turns out to be miles from your hotel, where you will give a presentation using equipment you’ve never seen before.

Even if you need to check a bag make sure you have all your vital stuff, plus sponge bag and a change of underwear and socks, in your carry-on.

Know what numbers to call if/when things go wrong.

Carry some local currency in small denominations.

If travelling with colleagues, rendezvous in the lounge, not the departure hall. Their just-in-time comfort zone may be very different from yours. Agree that you will all check in independently and then if you have to wait for them or vv it can be in the productive comfort of the lounge, not in front of the check-in desk.

Have you really checked into your hotel on the right day? If you are going to arrive in the early morning remember to check in for the night before.