What do you wish someone had told you?

My husband and I are about to take our first trip to Lisbon in a few weeks. I've been doing all my "homework" by researching and reading various posts here and in on other forums, but there are some things that can fall through the cracks or the info could be a bit out of date. Plus I'm just plain curious My question is this: for those of you who have already experienced Lisbon, what did you discover you wished someone had told you before your first trip? Did someone give you advice that you found particularly helpful or useful that you'd be willing to pass on? Anything from communicating, how to deal with scammers, public transport, finding and using public toilets, supermarket general etiquette, restaurant behaviour, cultural "quirks" particular to the city