I already used highlighting and comments when I read book. My high school english teacher taught us to highlight important things while we read book. I didn't highlight when I was in high school, but I started to do it after I get in college.
I really agree that highlighting helps to read critically. I use highlighting especially when I read my bio book. Usually there's too much reading each week and it is hard to remember all that when I study for exam. So, I started to highlight the things that I think important and hard to understand and read all the highlight sentences one more time before exam. It helps me to save my time and study effectively.
I also write notes while I read because that helps me a lot.

I find that highlighting is

I find that highlighting is only useful when you're trying to highlight important vocab words or other information where you want to go back to for studying or for a paper. If you just highlight as you read and don't go back to it, it's useless. Writing notes out on the side also help too, but usually I don't really know what to write. I find it helpful to write notes out in word or notebook while studying, that way I have a study guide made up while I'm reading where I can just refer back to and print out.

Thank you for your advice,

Thank you for your advice, and I forgot to mention that I highlight the important thing only while I read. I don't highlight everything because as you said it would not be useful if I highlight every single things.

Highlighting is also

Highlighting is also something that is a very useful tool. It works for me, but I know that some people find that it doesn't work for them. I also agree that making notes in the margins when you are reading is very useful.