The Scandinavian is easy to learn and you can play it against first move e4 all the time.
The Scandinavian Defense Wahls Set Up is for beginners and advanced chess players who need an opening against 1.e4 and want learn openings fast and don't intend to invest much time learning the opening theory of many openings. The Scandinavian is your answer to the first move of White 1. e4.
The idea is to avoid learning countless variations of the Sicilian Defense, the French Defense or other systems...
You just learn the Scandinavian and that's it and you have the answer to 1.e4. This opening is not popular with top chess grandmasters but perfectly suitable for beginners and advanced players.
I recommend the Wahls Set Up. Mathias Wahls is a German grandmaster and researched this opening very deeply and played it with success for many years.
You can learn the Set Up in a few minutes, just look at the image below and memorize the position of the black pieces and the pawn structure for Black. Forget about the white pieces for now. Make sure you put the black bishop to f5 and play e6 afterwards or you lock in your bishop.
Replay the games below and watch the different set ups for White. Sometimes he castles long and sometimes short or he attacks the f5 bishop right away. Learn how Black will handle these problems and memorize these ideas to apply them in your own games.