The following e-books are OER and free to access/use.
College Success (Concise Edition)
College Success (Full Edition)
This book is aimed at high school students, but I've found that it explains a few things better than the standard College Success ebook.
Tips & Tools from The Writing Center at the University of North Carolina at Chapel Hill
Chapter 3, Reading and Notetaking from College Success from OpenStax
Time Management Tips for Students
Most websites on body doubling are framed around ADHD, but this is a strategy that can help anyone.