Make friends with the staff on a cruise ship. They will make the days at shore that much more fun.
Do not store your brand new tennis shoes below the bus in Costa Rica
Do not travel through the Paris red light district at night with your bags, unless you are lucky enough to have a Parisian taxi friend.
Bring a blanket if you are going to sleep in Heathrow.
Sit and watch people while eating a big bowl of chips on a side street in London
NEVER miss the chance to see the Queen even if you have to stand in one spot for three hours
Eat as much Gallo Pinto as you can while you are in Costa Rica..or you will miss it. Pura Vida!
When you visit the U.K. be sure to talk to the locals. They have tips from where to get the best chips to where you should go to catch a glimpse of the Queen. Standing to see her for four hours was worth it.
When going to another country, understand the different sizes in clothing. It can be rather annoying trying to figure it out by guessing.
Always get together with locals - they will show you places you would never think of=)