Before leaving for Prague, I did a quick online search to see if I would need a SIM card in Europe or could I survive without it. Both options seemed feasible, but I decided to not buy a SIM card and avoid the hassle of reading too many details on what company's SIM card and what recharge plan to buy.
Countries that I had planned to visit were, Czech Republic, Austria, and Hungary, although I did not stick to the plan.
The two things that I relied on were offline google maps (that is the most important thing), and free WiFi hotspots.
I downloaded Prague's offline map before I reached the city and had taken a screenshot of the directions on how to reach the hostel, i.e, the bus, and the tram options.
A funny story: When I reached my hostel, I spent around 5 minutes standing outside a wrong building and feeling desperate about not having a phone network. Incidents like these might happen a few times, but don't be discouraged because you'll be able to figure out a way :)
Google Offline maps were a great help throughout my trip and I made sure to download an offline map of the city that I'd be visiting next.
Another thing that I did was, have a rough plan of my next day ready including the restaurants that I wanted to visit that day. I would add all the stops in my maps and select the walking option (because that's what I normally do) and follow that route.
The problem with this was, sometimes I had to change the order of stops or add a new place in my itinerary, then I would either go by the traditional way of asking people for directions or just navigate using the car option and judge if it's okay for walking or not.
Now, if everything above fails, all you have to look for is a free WiFi hotspot or go to a cafe/restaurant as most of them offer WiFi if you dine in. You can now do all the stuff, getting social media updates, talk to your family/friends, share pictures and navigate to your next destination.
I would say, it's not very tough to travel without a SIM card, rather more exciting. It's crazy figuring out a way when you are lost in the most secluded places and coming out alive.
All the best and safe travels!!