A lot of body builders uses an excelent technique to build muscles, i use that too and got great results. So, you apply the first rule of 6-12 Reps. When you get to between 8 and 10 rep, you should be nearly falling on the lifting, yeah! Thats a FAILURE, you have to reach that failure, because you exhaust your fibers, but no all of them!, so you go 2-4 reps after the failure, doesnt matter if you cant do the whole motion , if you got the half of it, you count it! So, go to the failure and then you count 4 more reps after the failure! And with that my friend, you will recruit the other fibers that we didnt work at the "easy" part of the exercise!
Advice, why should you watch body builders training/routines/ techniques?? They live "fitness/Weight training" 24 hours/ 7 days per week! So they will give you, really good advices, and techniques, study them! Nutrition/Training/Routine, but put a filter on that! Apply everything you want to try or learn, with a supervision of a professional!