I never bothered to print out boarding passes in advance... after all, the machine at the airport takes about ten seconds.
Here's the thing: at some airlines, the machine stops working 30 minutes before your flight. Leaving you at security to watch through the window as your flight takes twenty more minutes to board and leaves without you.
Tip 1: print your boarding pass out ahead of time.
Tip 2: if you forget, have them switch you to a later flight, then run to the gate of your original flight. Ignore them when they tell you that you'll never get on. I did.
We shouldn't need to share travel tips. "Have a good flight," he says sardonically.