There are a number of threads in this sub-forum regarding how to study. Your question is so general, its hard to know what to say except ... you're doing fine, but let us know if you face a specific problem.
I understand you're looking for key words, but when you study a chemistry text, or worse still, a mathematics text, you'll discover that its all key words. Back in the day, we used to use highlighters for bits of English literature texts we wanted to be able to find later. Trying that with science texts soon became pointless -- you eventually highlighted everything.
A better choice is to practice the problems at the end of each chapter. If those problems are simple definitions, be sure you can answer them -- no need to write down the answer, in those cases, its just a reading comprehension check. If there's a calculation, then definitely do it on paper, your working is what you'll study.