Quoting Rip: perfect is the enemy of good. On the other hand good technique is essential, especial at novice levels. I don't know why are you struggling with 135 on the squat, but I wouldn't be nit picking on every little detail though. As you progress you'll begin to feel your body better, and will notice when something is not being done right. Videos to check after you complete the set are also useful (and posting on the technique subforum from time to time seems to help).