Do not attempt to write too much. Organize your notes as you write. Two outstanding features of poor notes are that the speaker's vocabulary is copied and there is a great lack of organization. Listen attentively to distinguish between essentials and non-essentials. Essentials are the facts or theories of the matter being discussed.
Explanations are next in important, sometimes essential.
The non-essential materials are introductory statements, illustrations, transitional paragraphs, etc.