Using proper weight lifting form during any strength training exercise will improve/speed up the results you both see and feel. In addition, and of equal or greater importance, the injuries that can be caused by using poor form will be greatly reduced over the coming years. I have personal experience on the negative side of this discussion that I will share with you below. After that, I will give you some tips on good weight lifting form.
My first experience with weight lifting was in 1975. I was in junior high (now referred to as middle school) and played 3 sports. Our football coach started a summer weight lifting program. Not having lifted before, but getting the sense that it would be a good idea, I signed up and have never stopped lifting in some way, shape or form since then.
Looking back, I now realize that even though we used some very basic exercises (bench press, curls, various leg exercises on an Olympic weight machine) I was not using good weight lifting form. Being very competitive, I wanted to lift as much as guys that had gone through puberty well before me and out-weighed me by 30 or more pounds. Of course, genetics and physics being what they are, this was really not possible, so I arched my back and contorted my body any way possible to geak-up as much weight as I could. I got stronger, but it set the stage for all my joint pain and impingement that I live with today. I am not blaming anyone. None of us knew any better and the coaches could not watch 30 of us at once. They were just glad we were there putting in the effort.
I also suspect, that I would have been a lot stronger and had a better physique if I had used good weight lifting form all along.
There are some basics, visually, that indicate good lifting form (see the picture above). Head up, spine in its natural position, proper hand grip, feet on the floor. All those things are the baseline for good weight lifting form. However, in my mind, it's so much more than that.
First, and foremost, select a weight you can handle (unlike my personal story). If you are just starting out and don't know, go light and work your way up to more challenging weights. This will help you build muscle memory of keeping the weight in a safe position. It will also help you learn how to keep the weights under control. You don't want to bounce them off your chest, drop them on the floor or let them swing back to the starting position. Smooth, controlled range of motion is what you want. Have your muscles fully engaged during the entire movement. Control the weight; don't let the weight control you.
That leads me to the second criteria for good weight lifting form. Do you feel safe doing what you at doing? I know, it is subjective. However, after 40 + years of lifting, I know instinctively if I feel safe doing a particular exercise. I have pushed the envelope over the years and know where my safe zone is. Err on the side of caution.
Now that you have selected your exercises and the weight, how does it feel when you lift? Is there pain? I don't mean the "burn" that we all feel (and crave) in our muscles when we push them to the limit. I mean is there any sharp pain; particularly in your joints or back? If so, change how you are doing the exercise. Are your hands too far apart? Are you leaning too far forward or back?
Finally, understand, for each exercise, what muscles the exercise is supposed to target (Curls target the biceps. Bench press targets the pectorals in the chest, triceps on the back of the arms and shoulder muscles). Focus your mind on those muscles. Do you feel the burn in those muscles?
I am very happy that you want to lift weights, grow your muscles and burn off body fat. It is my hope and prayer that you will learn from my mistakes and not have to live with poor-form-induced pain. I'll see you on another page.