When you start working out, you have to design your program with scientific way to insure safety and good results. it means that you have to train hard but with smart way. To be able to build a good, and well proportioned body. you must combine doing free weight movements with machines, but make sure you do 70% from your workout with free weight. Free weight exercises is good for: Bulk, size builder. Can do compound exercises with free weights (like squats) to make sure you are training all types of muscles and fibers. You have to make sure you have a spotter with you when doing heavy weights to avoid failure. Machines: its an isolation movements that works only the targeted muscles, exp: if you are doing leg extensions, it means that you are training only the quadriceps muscles, but doing squats means training the quads, hamstrings, gluts, lower back, upper back (compound exercise. Very safe on joints, cartilage and ligaments. Can do many reps on it and not like