1. Starting too heavy
That’s the most common mistake. If you are beginner just start every exercise with an empty barbell except Deadlift (you can start heavier here) and add weight every week. If you’ve been already training for a while and you know your maximum 5 reps don’t start from them. Remember that you have to brake your personal records in about fourth week, so lower weight a bit. You have to give your body few weeks to adapt to constantly lifting heavier and heavier weight. Once it will adapt, you will be doing progress for much more longer than that. But if you won’t give it enough time you’ll stall after 2 weeks and it will be over. Be patient with this workout. After only 2 months you’ll be amazed with the results. I’ve never thought I could be as strong as I am now. So leave your ego at home and start light.
2. Using too big increments
The same thing. I know it feel stupid at the beginning to add 5lbs (2.5kg) each workout on the Bench Press when you can add probably 30lbs and lift it. As I said, be patient, give your body time to adapt. After 7 weeks you won’t think that these increments are small.
3. Adding more exercises
You don’t need any more exercises, trust me. During workout A and workout B your every muscle will be working. Don’t worry about your biceps, it will be working during Chin Ups and Rows. I said it before, power-lifters don’t do Biceps Curls or Triceps Extensions but they arms are really thick.
4. Not squatting
Actually it would be better if you dropped any other exercise and do only the Squat 3 times per week. This workout is based on Squat so don’t avoid it. Start light and you will get use to it. I bet you after 4 weeks you’ll change your mind about it. You’ll love to Squat, when you realize how effective this exercise is.