It's far too easy to tune out during a lecture if you've already dismissed the course or subject matter as dull and uninteresting. Work to find a point of relevance within the information that's being presented and connect it to areas of study that you may be more concerned with. Over time, this connection will serve to change your perspective on the course--you may even find yourself looking forward to lectures you used to dread attending.
Attempting to write down everything you hear during a presentation is both counterproductive and exhausting. By listening for a professor's buzz words and phrases during a lecture, you can be sure that you're recording the most essential information. Phrases such as "most importantly," "furthermore," "additionally" and "to conclude" all signal a transition to a key point or main idea. Also listen for terms or concepts relevant to the course, such as specific names, locations or dates.
Forming a friendly relationship with your professors and teaching assistants at the beginning of the quarter is always a good idea for several reasons. First, it makes asking for a copy of a missed lecture or an extension on a paper easier--if they know your face and know that you tend to be engaged in the course, they will be more likely to oblige your request. Second, the fact that they know when you're in class, and thus when you're not, will encourage you to maintain good attendance. Third, you'll know where to turn if you need a letter of recommendation or faculty endorsement later in your college career.
Make your way to the front of the class or lecture hall at the beginning of each meeting. Sitting toward the front is a sure way to maintain focus on the professor's presentation as their eyes will be on you, or at least skimming over you, fairly regularly. If you are easily distracted while sitting next to friends or study partners, relocate to a more isolated seat or politely decline their attempts to socialize during a lecture.