Sirius just made a comment about weight lifting on Bumight's post, so I thought I'd share some of the things I've been taught about lifting, and strength training in general.
1. Ditch the heavy weights. Except you are body building or wrestling, for example, you do not need heavy weights. As with all your diet and weight loss activities, the following principle also applies to weight lifting: 'Quality over Quantity'. For toning and shaping, you only need smaller weights and your body weight. Instead of straining your muscles to do 1 set of 10 reps of curls with a 15lb dumbbell, do 3 sets of 20 with 5lb weights. Engage your body weight with push ups, pull ups, leg raises, arm raises, planks, etc.
2. Mix it up. Don't over work any muscle groups. Set up a calendar that helps you properly schedule your strength training in a way that your muscles have time to rest and repair before you work them again. If you do biceps, triceps and shoulders on Monday, hit HBT (Hips, Butt and Thighs) on Tuesday, then ABs on Wednesday, etc. Your muscles with thank you for being kind to them.
3. Be Consistent. Muscles are like high-maintenance girlfriends. They need constant attention. Don't abandon them. Keep showing love by working them out. If you ignore them, they become rebellious and turn to fat.
4. Don't forget the cardio! You have to make sure that you are not just building muscles under layers of fat. Muscle training doesn't replace Cardiovascular activities in your weight loss / workout program. Keep your heart rate up. Rope Jumping, Jogging, Step Aerobics, Swimming, etc are good ways to get your cardio in.
5. Eat Right Baby. Don't be scared to count calories. Listen to your stomach. Don't overload it. Don't stuff it with a heavy dose of carbs if it will be just fine with veggies. Be kind to your behind.