Don't copy exactly what the instructor says: listen and think before you write things down. If it doesn't make sense, be sure to ask about it after class! Put notes in your own words, so that it makes sense when you look at it later.
Write the topic and date on each page of your lecture notes, and organize them accordingly.
Use abbreviations to help you take notes faster, and keep them concise.
Indent to show subtopics and details, and leave space vertically to indicate a change of topic. This also helps when you review your notes and find more things to add in later.
Use symbols to indicate words, phrases, or ideas you think you may have missed or not understood, and ask other students or your instructor about it after class.
Leave space on the side of your notes to identify key words and questions you may have about the content.