Actually, you should go back and read/view again the "basic" tutorials you think you already know.
For example, I'm pretty sure that in Yann and I's online class we talked about loops such as "for each".
Those course were a lot of informations to digest and are worth going back to. With how the "basic" informations have already sinked in into you, those lectures can offer you another read/layer of given informations.
Don't hesitate to look back at my tutorials too (shameless plug) where I always try to explain this kind of behavior.
Asteroid clone in less than 100 events as well as the video tutorials I did for gamedev tutsplus.
Also, never forget that Construct 2 relies on some of the same principles as regular coding. So somewhere along the line, you can read about those principles for "true languages" and still adapt this knowledge and apply in the frame of C2.
Finally, you can read tutorials as much as you want, I believe you can't get around the actual experience of making your own games and mistakes that you'll learn the most from.
It's like for anything, it is years of practice that help you achieving mastery. And it takes time, trials and errors, no magic recipe or ultimate tutorial/book there unfortunately ^^
I hope this answer helps nevertheless !