1. Don't be intimidated! - Many are nervous to use the transportation options in Europe, but it really is not complicated! You will get the hang of it within your first few days.
Kaptan and I are from California, so the most common form of transportation is a personal car. As you can imagine, metros (subways), trams, trains, ferries and busses were a bit of a shock for me.
However, I quickly learned that there are a ton of information booths, maps, and apps that make is extremely possible to quickly learn the easiest ways to get around.
2. Download Google Maps and GoEuro- Just like you would use your phone's maps/ gps to give you driving directions, these apps will give you all the public transportation options you need to get to your destination.
Google maps will explain step by step what bus stop to get on. What time it comes and how often. What stop to get off and what metro, bus, or train to transfer to, until your are right in front of your destination.
GoEuro is a more helpful for longer distance commuting like Paris to Brussels. It will give you different trains, buses, or even Blahblah cars (kind of like uber) to take and layout the different prices.
3. Use the information stands and maps- You will find a map and a list of all the different stops at each metro, tram, and bus stop. Also when you are inside a bus or metro there is an easy map to follow along to to keep track of what stop you need to get off.
Kaptan and I didn't have unlimited data our first trip to Europe so these maps and information stands were key for us. Paris, for example, is very good about showing where each metro, bus and tram line goes and connects to each other.
4. Save your money! - When you are about to use public transportation it is rare that it is free. The only free example I can think of is the ferry in Amsterdam.
When you are about to use a new form of transportation or are entering a new country go to the information desk or ticket clerk and ask what deals they have that would fit your travel needs the best.
Paris offers a one day, two day, week, or month long pass that is unlimited use of busses and metros. They also have deals if you are under or over a certain age. You can even reduce your ticket prices further if you only want to go to certain "zones" in Paris.
As far as trains, in Belgium they have what is called and 10 train pass. You pay a discounted priced for 10 train rides upfront and use them anywhere in Belgium and anytime you would like. Kaptan and I bought it this year because we will be going back and forth through out Belgium quite a bit this month.
When you talk to a ticket clerk they are use to people looking for the least expensive ticket that fits their situation, so just ask!
I hope this helps with any upcoming Europe trips. I'm happy to answer any questions! DM or email me.