Textbooks are normally the introduction to a topic. Avoid reading ‘passively’ by highlighting or letting your mind wander as your eyes skim over the words. When you read something important enough to highlight, write it down. This will help you when you revise, and will help you remember it. This is especially important when you have to plough through long blocks of dense text.
Very similar to the tips given in the journal section – except read the introduction and the chapter summary rather than an abstract. It is also a good idea to pay attention to the words and bullet points designed to stand out in the text – they are there for a reason.