New tactic

I've played chess for a day or two after studying the individual moves of each piece for a weekend.
I've come to realise there are a few specific strategies that give very specific advantages when played.
Whenever I see someone play by the book, I will purposely play a "mistake" that prevents them from continuing to play by the book.
This will usually result in the opponent either make a bigger mistake, or make use of the mistake.
In lower leagues (750-), the opponents who play the book plays by it usually because they can't think of how to start properly.
By messing yourself up, you will make them overthink to the point that their brain lags for the remaining of the match.
"You can't predict what I am about to do if I don't know what I am about to do".
TL;DR: To go beyond lower league, simply avoid playing by the book.

This is my first post, please have mercy.