(1) Ask questions. If you are not sure about something the teacher said, ask. Chances are you are not the only who did not understand. Don't wait for someone else to ask questions to which you want answers. The teacher is not a mind reader, sometimes they can read confusion in facial expression, but most times they will have to be looking directly at the student. So ask questions. It is better to ask for clarification rather than assume that you know what the teacher is talking about.
(2) If possible pre-read the text for the next day's lesson. This is especially applicable to students who have multiple textbooks. If the teacher said what will be on the agenda for the next class meeting, read the material. If not, ask. When you read use Cornell Notes to document what you read. You can find out about Cornell Notes and see templates by doing a Google search. Then take your notes to class the next day and add to them when the teacher goes over the information in the textbook or does the lecture (direct instructions). Reading ahead of time will help you to determine what you already know about the topic, what you thought you knew, and what you really don't know. This will help you to focus on the information that teacher presents in the class. At the end of the day review your notes and make any necessary corrections; write notes in the notes area that help to summarize that lesson; and finally look over your entire stack of notes. Do the same thing the next day. You will be surprised at how much you will remember.
(3) Have positive mindset. If you think school is boring, think instead of what you want to accomplish in the short term. To do this, set goals for yourself and visit them every day. Start with short term goals. For example, since I started college one of the things I do with every class syllabus is turn to the grading portion and write: GOAL "A" then every day I ask myself what have I done to earn an "A" in that class. I have a few "B" on my transcript but that is OK, because I know I did the best I could or in some cases I know I could have done better. But the key here is to understand that I know what it takes to earn an "A."
Three keys to start the year off right - ask questions, pre-read the next day's lesson, and have a positive mindset.