Doing cardio before or after the workout depends on your goal. For instance, if your primary goal is to gain muscle and/or specific strength/power performance, you would do cardio after resistance training so that your energy and glycogen levels are highest at the start of training. If your goal is body fat loss, it doesn’t really matter before or after. If aerobic endurance is the goal because you’re an endurance runner, cyclist, swimmer, etc. you would do resistance training well after or long before your regular endurance training, or simply on a different day.