For Students : I wrote this book partly because when I studied this material as part of my own Computing degree, I had to work really hard to understand the material, a situation which arose not because the material is too difficult, but because it was not well presented ...
from Preface of A Concise Introduction to Languages and Machines by Alan P. Parkes, Springer 2008.
I have seen video of a lecture on MSRI where the researcher / professor held 'a talk' ( there is a subtle difference between 'a talk', a presentation and a lecture, 'a talk' is a euphemism for a not well prepared presentation ) about a subject from scribbled notes. Most of the lecture he stood with his back to the audience mumbling while scribbling math. End of lecture. Goodbye. It was expected of the audience to write up notes from his mumblings and scribbles. - Folk like that, probably based on a brilliant thought they had decades ago, get the opportunity to write books too. Once in the hands of ( then ) students like Alan Parkes they make the learning experience troublesome to say the least.
Well written, illustrated mathematics followed by examples, more examples, examples of exercises, exercises with written solutions and so forth make studying mathematics easy. ( Think of an Open University booklet, a good one ). Open University booklets are written by course teams for students and not by professors who write to impress... who actually?
Tip 4: Change booksIf you have difficulty with a ( mathematics ) subject then find another book about the subject. Check how the other author explains the topic. Try a third, fourth if necessary. This method is guaranteed to work. When you are close to revision for an exam it stimulates to read through the material written by someone else. Different exercises, and so on.
Finally: authors who write for students are read, respected and remembered.