Ask as many questions as you want! I'm super happy I get to help :)
I feel your pain with Grammarly. I wish I could get the Premium version, but my parents won't let me. I tend to watch for the little yellow circle and when the number gets higher, I try and fix my mistake unless I can't find it or it's a dumb suggestion.
I tend to get an average of 90 for my overall performance. I think it's because I've been writing for so long and I'm just used to how Grammarly thinks.
But yes, serving to do better is a great way to get better! As long as you don't push yourself too hard, it's a very efficient way to get better at something.
From my personal experience with reading and writing books, the ones that have a unique aspect to them usually draw the reader's attention more. Also, if you add in something that will make the reader go "wait, what??" then they will defiantly want to stick around and continue reading to find out their answer.
Cliffhangers are a great way to do that, but you obviously can't make every chapter a cliffhanger. Instead, you can add in some sort of mystery that the readers will get hints on the more they read.
I hope this is all making sense <3