Stop, reread the question and rework the problem. Work the practice problems on reserve. Do your best to work them first, then look at the answers. Always carefully proof read data entered into the computer before conducting any analysis. It's usually easier to proof a hard copy.
Exams Find out the format and material to be covered when an exam date is announced.
Anticipate likely questions and prepare for them. Do not cram. Get a good night's sleep the night before the exam. Practice for the exam by working practice problems with a self-imposed time limit. All exams will be limited to 50 minutes and you need to be comfortable working with time constraints.