There is a reason that so many lectures have mandatory attendance. They clarify and contextualise the subject matter and offer the opportunity to ask questions.
To optimally prepare yourself for a lecture, it is important that you familiarise yourself with the required reading and any previously treated subject matter. Creating a summary or mind map of the text(s) is a useful tool for achieving this. If anything seems unclear in the text, trust that it will be addressed in the lecture or that you will be able to ask questions during or after the lecture. It may be advisable to review your notes from the previous lecture if the upcoming lecture will cover similar material.
It is impossible to retain all the information offered in a lecture. That is why you should take notes. Pay special attention at the start and end of the lecture, as the overall structure is often announced at the start and the end usually offers a summary or conclusion.
Not a swift writer? Write down key words or phrases. Even these will prove helpful when you review the PowerPoint presentation of the lecture later on. Don’t attempt to transcribe the whole lecture. Instead, try to distinguish between the main issue and any side issues. It is a good idea to leave marks in your notes that create a clear visual distinction between the issues, the examples, and things like references to the literature.