1. Buy Transit Tickets
There are many ways to get around Prague. You could rent a car, hail a taxi, walk, über, or what I highly recommend, public transportation.
When you first arrive to Václav Havel Airport you will see several people entering metrobuses . DON'T PRESS YOUR LUCK & FOLLOW SUIT. There's a kiosk to purchase either a 30 min, 90 min, 1 day or 3 day ticket. These tickets can be used on every public transportation system.
I've learned that czech culture has an honor system that everyone abides by. On my first trip, the ticket expired within the hour and there happened to be a monitor on board checking. Long story short, if caught you'll have to pay a fine and CASH ONLY, they'll even escort you to the nearest ATM.
2. Make Sure To Carry Cash
Not all but most of the places and attractions will only take cash. But, it's not hard to do when you pass 10 ATM's while walking down the street. I'm not too sure about most countries, but the United States is well accustomed to just swiping our debit or credit cards.
Also, You may have to pay to use public restrooms.
3. Respect The Quiet Hours Of The Night
I know everyone would like to get a glimpse of the nightlife no matter what day it is. But once the bars close you have to respect other people who live nearby.
We all make friends when going out and don't ever want the night to end, but just be mindful of other's situation or guess what, you'll have a fine to pay and by the Czech Police. But from experience, they'll only take the cash you have on hand at the moment. And thank goodness it wasn't a lot. (Spent it mostly on beers).
4. It's Okay To Drink In Public
I was so amazed the first time I saw people just drinking on public transportation and I'm not even referring to drunken homeless people. Don't be afraid to crack open a beer or pop open a bottle of wine at a park, on the street or on the bus. It's perfectly normal!
5. Common Courtesy
This should be second nature but it has to be mentioned. Whether on the bus, train, or tram and you see elderly people or a mother with small children, please give up your seat. Or at least offer.