First and foremost, familiarize yourself with the schedule of your transportation mode of choice and know of the night hours and alternative ways to get to and from, as not all services run around the clock.
Resources for Transport in Stockholm
If you are going to a new place for the first time, find out which modes of transportation are best to use by plotting your journey on sl.se or download the mobile app Travel Planner STHLM Traveling – SL Planner.
This real-time transit website and app helps you get from A to B. It contains all private and public transport modes in Greater Stockholm. The app uses all the local data from Swedish transport agencies and is available in English.
There are several other European cities on the app (Rome, Paris, Brussels, Berlin, Copenhagen, to name a few!), making it a good resource while on certain DIS study tours and independent travels.