Its a common misconception that working one or two body parts a day is the proper way to divide your workouts. This is a fairly recent trend that has been circulating for the last number of years and was made popular by weight lifting magazines and internet columns. Two things happen when you attempt to divide your workout up in this manner. First you tend to overwork each muscle group (especially your smaller muscle groups) and second you only work each muscle group once a week in most cases. Remember INTENSITY is the key to great results not more exercises or more sets.
Skipping your warm-up – not warming up before a workout significantly increases your risk for injury, even if you are only planning a short workout.
Waiting for equipment – your rest period between sets should be kept short; waiting for equipment could give you too long of a cool-down, making your workout less effective. Always have a backup plan in mind incase the equipment you are heading to is occupied.
Not having a plan – to stay on task and have an effective workout, always have a workout plan ahead of time so you are not wasting time planning your next move.
Having the wrong plan – performing your cardio first could fatigue you too much to have an effective (and safe) lifting session. Complete your lifting first then head to cardio.
Performing the same old routine – completing the same exact workout every day will not only get boring, but will also stall your results. Mix it up every couple of weeks.