Was this guide intended for total begginers as well?
If yes, in my opinion it feels like it could talk more about basic stuff (like explanation on offensive / defensive kill rates, distribution, ensuing efficient expansion; some keywords you mention could also be described in slightly more detail - safety, cluster, counter etc).
It would also make the transition to more advanced stuff a bit smoother.
What mindset you should have while picking?
Whenever I pick I rarely think of what my opponent might do.
I don't care what my opponent does, and want to focus on my own game plan.
I think this is the only part I actually strongly disagree with. To me, it is important how good my opponent actually is.
When I decide on picks, I roughly estimate what kind of picks my opponent might do / not do, and what kind of game we will get as a result - how fast we are going to meet, how we are going to attack each other, and how complicated game will be.
Having that assumption, if I don't like the chances I get from my picks against the specific opponent, I go back to picking a different strategy, or choose picks more fitting the assumed game scenario.
I pick differently depending on whether I think the opponent is worse or better than me. Also, it's good to mix the picking strategy up, to be less predictable, so I sometimes pick and play like a total shit too.