Read and reread the text. Scan through the text quickly the first time, just to get a sense of its contents. Read more closely upon the second read. Make simple marks on any important or eye-catching passages, or mark them with Post-its.
Start annotating. Circle or underline important, interesting or surprising passages. Write comments in the margin. Use your own abbreviations. Write down questions you have if you're confused and ask your professor later.
Write down and mark important plot points if reading fiction. Make note of any defining character moments or conflicts. Also take note of any symbolism that takes place in the fictional text.
Write down any connections you notice between the text and other texts from class. Also think about how it connects to the professor's lectures.