This is one of my favourite books and though rather dated (the last game cited is from 1948) it's also extremely instructive.
In 100 annotated games, Konig discusses the opening theory of four openings: the Ruy Lopez, Queen's Gambit, English Opening and King's Gambit.
It takes an evolutionary approach to chess theory, and instead of jumping in to contemporary theory, tells the story of how that theory came about. So we trace the English Opening from Staunton's new(!) approach in 1843 to Golombek's ideas in 1939.
The Swiss Defence gets its name from Henneberger, a Swiss player who, among other games, tried it in a smul against Alekhin in 1925. He played strongly, and that may have alerted Alekhin to its potential:
opening will rest (or should rest) on several
considerations: your style and temperament as
chessplayer, your time and aptitude for study,
ambitions as a player. The standard recommendation
Black counters in the centre, provoking an immediate crisis. White must defend or dodge.
The Caro Kann has a reputation of being a boring defence. It is quite deserved, I believe. Black aims for a solid position where White's space and activity can be held in check and in the end neutralised by exchanges. It is a system free from weaknesses and has been popular among top Grandmasters for many years.
It is not, however, your best choice if you want to play for a win, unless your technique is very good.
You have to be able to make a decent start in a game of chess, or you risk being blown away by your opponent's better development. Knowing a few openings in a bit of detail is some insurance against traps and ideas that you haven't seen before.
So, here are some variations in common openings that you can -- and should -- learn. At each turn, try and learn not just what is the right move(s) but why that move is preferred.
Your style: are you a Steady Eddie or a Bonkers Billie?
Your memory: can you commit the key traps and variations to memory?
Your study time: can you find and absorb what you need to play this system well?
Your aims: are you trying to get a playable position? are you trying to
set your opponent problems, so they make a mistake? are you inviting
your opponent to waltz with you blindfold on the edge of a cliff? are
you trying to lure them into unfamiliar territory, or a trap?