I couldn't link to the reddit article this quotes, maybe other readers can. The Local article spells out a lot.
This direct link to the Redit article works for me: https://www.reddit.com/r/france/comments/6jrelt/so_youre_going_to_take_the_metro_in_paris_this/
- The lines are not deep, they are mostly just below street level. This has the disadvantage that when the stations were built, they were built with stairs down to the trains. Unlike the London tube, which has escalators coz' its deeper. Be prepared for a lot of stairs.
- Always know your line number, and the end station. Unlike the London tube, where the lines are signposted north/south/east/west, the métro says "direction (name of final station)".
- Interchange stations often have long walks, and more stairs.
- The first time you exit any station, it will always be via the exit the farthest away from where you want to be ☺.
The Paris Metro Map app is aces. Works like GoogleMaps. Plug in a to and from metro stop and it tells you what lines/changes to take. It's free or pay a couple of bucks to get rid of ads.
Or, you could just purchase the time-honored little blue book, "Paris, L'Indispensable" for all your Metro, and Bus needs. Included are all the streets in Paris, so you won't get lost. Only about 6 EU, in any newsstand, depending on neighborhood.
No WIFI needed.
Yes, Chexbres, that was my first thought! My copy is tattered from use but is indispensable. To use it all you need is to be literate.
Will you have a smart phone? I love the metro app.
Literate and eyes under forty years old--but I still use it, even to answer questions here.
If you need a detailed bus plan, you can buy another blue book "Paris Bus - L'Indispensable" - lists all stops in order in each direction, a 2-page spread for each bus line and a schematic showing where the bus goes.