I do a combination of both machines and free weights. Go to the library and get Arnold's book on body building. It is really great. Alternate your body parts. Here is my workout schedule for the week just to give you an idea.
Sunday- Chest and tricepts (incline press, pec fly, decline press, assisted dips, push-ups, overhead tricept extension and tricept pull-downs)
Monday- One hour of cardio and abdominals (I am constantly changing what I do for abs)
Tuesday - One hour of cardio (no weights)
Wednesday - Back and Bicepts (Lat pull-down, compound row, assisted pull-ups, preacher curls, hammer curls, forcept muscle curl)
Thursday- Legs (hack squat, inner/outer thigh machine, calf raises, leg kickbacks) I do my legs on light weights with high repititions for toning.
One hour cardio class
Friday- Shoulders This is where you can create the illusion of an hourglass shaper (overhead press, lateral raises, frontal raises, rear delt, weighted arm circles)
One hour cardio class
Saturday - REST DAY!!
I didn't build this routine in a day. This is the culmination of many months. I have been working out like this now for about 2 years. Never work the same body part without at least 24 hours of rest. TAKE IT SLOW!! Make sure to schedule rest days. Check out men's health. There's even a weight training for dummies book. It takes about six weeks to begin to see results with strength training but it's so worth it.