Adding weight or reps is progressive resistance. I find it necessary to make any growth, and on a continuous basis. Form has some importance, but not as much as most would have you believe. For powerlifting technique and positioning is crucial to move more weight and shorten the distance the weight must travel. For bodybuilding goals form is important, as you do want to target the intended muscle, and you dont want to throw the weight around to the point of injuring yourself. But for me, I have my own form. I keep the tension constant on the muscles Im working, and always tear up the given muscle group very well. I like to incorporate cheat curls with the barbell at times, sometimes with the dumbells Ill go real heavy and throw the weights around a bit, maybe control the negatives. It varies really. I almost always cheat out the last few reps on curls so that I can hit complete failure. In a way, it takes the sets beyond failure slightly, since the arms are already numbed out for the most part. Sometimes I keep it stricter. I like to switch things up and do what I feel. Im not anal about form as some are. I do have some standards though. I dont lift my ass off the bench when flat benching. Aside from that, anything goes in moving that weight. My form tends to be good on most movements anyway, just from the years of training, so my focus is always the progression of weight and reps.