Probably the only tip that I can agree here with because I see it over and over with people, it don't pack too much.
Oh, I agree with most of the tips:
I'm with you on avoiding overpacking. My daughter is the only person I know who packs less than I do.
Verifying the limits of your phone plan is wise.
Checking the exact location of your hotel (compared to your destinations) is wise.
Closing your shampoo bottles tightly; well, I must admit I've failed that test -- now I encase everything in a ziplock.
Always pack good quality, comfortable shoes.
Do not buy large souvies that you'll have to transport.
Do check the legal requirements for coming and going to your destination.
Never use a credit card to get cash.
Always print out (or enter into your phone) your travel confirmation numbers, hotel address /phone, and more.
Did I know these things already? Yeah, but they're not all things that travel newbies would automatically figure out . . . until they're in a pickle.