If you decide to use free weights, visit your library and check out several books on the subject. There are standard lifting techniques that are appropriate for all ages. Also, the American College of Sports Medicine has recently published its Fitness Book. Always use good lifting technique. This is far more important than the amount of weight you lift.
Bad technique causes injuries.
Pay attention to your breathing. Breathe normally, but exhale when lifting the weight and inhale when returning it to the starting position. Lift 2 to 3 times a week. This will produce the best results. Even if you feel lazy on a weight day, do something.