I would do very low impact cardio, no more than 10 minutes, before or after the workout, whatever you prefer. Just to get your heart rate up and keep it there. Either way, I'd do a body-weight set of whatever lift you are doing for additional warm up and blood flow. None of this is really for weight loss, more for your heart and efficiency.
If you want to lose that extra weight, do sprints or some other similar high intensity workout (see Espi's post). 8-10 40 yard bursts is what I do, usually on grass as it's easier on your body. I'm 37, I have to think about such things. Ain't go no time for injury.