It isn't too difficult to play them, and it is not really true that you should start with tournaments first. I started with cash games, and am doing just fine with both MTTs and cash games now.
Some advices:
-think about bankroll, don't dive into higher stakes if you are new to the game,
-reading a book is not necessary, but some theory could come in handy, the alternative would be watching YT videos of cash games from some high stakes players,
-while you are playing, pay very close attention at what people are doing and how are they playing, especially if they show cards. You can use that to your advantage multi-way. You will better understand individual players and how to then play against them, also you will quite often be able to see how to play properly and how to NOT play (both live and online, people are making some very good plays and very bad once, so learn from their mistakes, rather then yours)