Pack light
Rent apartments when possible
Use ATM machines
See the Borghese Galleries

Many others, but I guess these are my favorites.

www.kayak.com.

Worth hundreds every year.

Pack light. Pack light. Pack light.

I have to also put in my two cents worth and remind everyone that this IS a forum and I believe forums are for people to share information. Obviously much of the information is based on each one's personal experience and opinion...am I right? Sometimes there isn't a right or wrong answer but I'm guessing most of us are intelligent enough to understand that we need to sift through the advice and take away what helps up the most. In my opinion...there is no bad question to be asked on this travel forum. If you don't want to answer it...then don't. Too many Fodor Forumites take themselves way too seriously and some hold others way too accountable for their opinions. Chill.

Lots of great general rules of thumb, but also tops on specific mechanics. When I was having trouble navigating a website to reserve train tickets several people guided me with prompt responses and saved the day!

Perfectly said, caroltis, my sentiments exactly - I am new to the board and almost didn't come back after the initial responses I got, they mostly had a very negative feel-however, I am glad I stuck with it and kept coming back because I find this site to be an invaluable resource, and like you said, take from it what I need. I hope to give back when I post a trip report after our 3 week European adventure is over at the end of June, in the hopes it might help someone with their quest. Thanks again to all who allow us to learn from you.
Leslie