The biggest mistake people do in the gym is that they try to lift really heavy and just swing their body to & fro. Instead of lifting heavy weights, you should concentrate more on doing quality repetitions while lifting as well as on dropping the weights. The term is know as ”Eccentric Motion”.
When you do the eccentric motion (while completing the repetition), you will feel the pump and stretch in your muscles immediately. Do not do the formality of lifting heavy weights and just dropping it off. Even if you are doing 10-12 reps, do it properly by lifting the weights slowly and follow the eccentric motion when you drop it.
Proper movement is more important than lifting heavy. Of course, lifting heavy is really important as muscles follow the strength but that should be done gradually and not overnight.
Lift only that much of weight which doesn’t affects your posture and movement of the muscle. For instance, if you are doing the biceps exercise then make sure that your shoulders and back is rigid and your complete focus is over the biceps.