Skim the lab instructions before coming to lab. You won't be able to understand things fully without the equipment in front of you, but you'll get a general overview that will serve you well and ultimately save you time. Don't be afraid to fiddle with lab equipment unless you have been specifically warned away from it. Many students are reluctant to play with electrical equipment because they're afraid of being shocked. Unless you are told otherwise, the stuff used in lab won't hurt you.
Tips regarding exams Keep up with the course.
Don't cram at the last minute. Get a good night's sleep. Even if you ignored the advice above and have to cram, limit cramming in favor of sleep. Prepare a one-page summary of the material being examined. Your teacher expects you to work with ideas and solve problems, not plug numbers into equations.