When you do an exercise for the first time, start slow and allow your body to feel the muscle (s) being worked through the entire movement. Focus your mind on nothing but feeling the muscle. When you do this, you are giving the body the opportunity to contract the muscle(s) being worked and figure out how to correctly do the exercise. This is also how you start to connect the mind and body and how you target the muscles that are suppose to be worked.
If you are just moving the weight and not focusing on the correct muscles, you body will use the stronger dominate muscles to do the exercise, and not the ones that should be used. As you learn to feel the muscle that are contracting you will gain a better understanding of yourself and what works best for you.
Feel don’t think! You will know what I mean if you practice feeling the muscle.