Narrow down the material provided for studies. Highlight important information you may be tested on only and then re-read that highlighted information only. Lectures never cover everything and always come with information you will not be tested on. (Yes, your instructor's experience can be interesting and helpful, but you will not find 99% of that personal experience information on your tests. )
To study, I used material posted online by instructors only. (Does your school post lecture notes online?) Books have way too many pages. Teachers often tell you to know everything which is tooooo much (30-100 pages a week or something like that? really? and you are having multiple classes? It's unrealistic.) I had multiple teachers telling me "if you do not know A and B, you will fail the class/PT school," etc. Well, I could never remember maybe more than 10% of what they told me I "must" know and was able to maintain GPA 3.7. So I think if you can narrow down information down to 3-5 pages per class per week and just study over and over that information that you can be tested on only, you will be able to improve your grades.
Internet is great, but again, there is tooooo much information there and you will not be tested on 99% of it. So stick to the material that your school provides only. Quizzes are good resource of studies for exams. Some questions from quizzes can be on exams as well.