There are different ways of annotating text. However, what is most important is that the annotation of the text should be properly done, so it will produce excellent results depending on your reasons for doing it.
1. One of the ways is by summarizing the key points in your own words. The use of headers and other words that are written in bold should be of help, and you must be able to understand the central idea of the text.
2. At times, all you will need to do is to circle important phrases or other concepts used in the text. Look for words or phrases that appear mostly in the text. Doing this will help to have a better understanding of what the text is all about.
3. Another interesting thing you can do when annotating text is to underline or highlight sentences. Doing this will help you to easily locate any information you need per time.
4. You can also put some questions or comments in the margin.