Weight training using free weights exercises usually incorporates dumbbells, barbells, a medicine ball or kettle bell. Advantages of weight training with free weights is that a greater range of movement is possible and all the supporting muscles (synergists) are also exercised. They can also be more explosive which is better for sports specific training.
It is very easy to start off right and loose your form as your muscles fatigue. Always think about your posture when performing strength exercises and start with a light weight and gradually build up.