I had to find them out for myself but I like to believe in:

- Lower your expectations. Expect most things to be passable at best (especially hotels, restaurants, flights, meetings, rental cars etc.) and you won't be disappointed.

- Accept that bad things will happen. The sooner you convince yourself there will be delays, cancellations, traffic, rain, passengers of size next to you, the airline running out of your selection etc. the happier you'll be.

- And, from my Mother, bring a book. Also, you can never have too much reading material.