For continuing success you need to be in the habit of setting high standards for yourself - and exceeding them. Tardiness and absenteeism are devastating in science classes. Being present in class and on time should be ingrained in your habits and be as natural as breathing. If you've always enjoyed learning and have a long-standing genuine interest in the subject then you'll naturally learn better. If you hate it and resist, it's going to be a rough road.
Science is logical.
For more depth, skim the summary to start then read deeply if needed. Don't read more than 5-6 sentences without stopping and mentally reviewing it. Take it slowly. Keep a semester calendar. Create both a daily and weekly list of activities and events.