Before the first lecture, read through the Course Outline and highlight the important information. Know what to expect, and any questions you have.
If they're available - they usually are - check the slides before each week's lecture. Get the topic, structure, main detail (information, theories, references), any activities, how the topics fit together (and how they develop from previous weeks), and any new vocabulary/questions you have. By the time of the lecture, you should have clear expectations about what you want from it and how it should fill in what you've already got.
Most lectures are recorded, but don't rely on that. If live lectures are available, attend in person (physically or by Zoom), and only use the recordings for backup and checking. It consistently means better marks, as well as (in most courses) the chance to exchange questions/ideas with other students and the lecturer in real time.