PNP #3: Simple Exercises Beat Complicated Exercises
When selecting exercises, simple beats complicated nearly every time.
When you train, you train to elicit some kind of training effect. When you choose exercises, you should be choosing the exercise based on the desired training effect. A simple exercise will have a relatively straightforward training effect. A complicated exercise will have a very cloudy training effect.
Once you start pistol squatting on a Bosu Ball while balancing a kettlebell on your nose, you know you've gone too far.
That's an extreme example, but actually don't program anything involving a Bosu Ball, they're a waste of time. Also, if your trainer programs any exercise with an upside down Bosu Ball, fire them immediately.
Also, don't confuse a SPECIFIC exercise with a complicated exercise. A specific exercise is trying to elicit a specific training effect.
For example, 45 Degree Incline Dumbbell Curls with a Supinating Offset Grip is a specific exercise. During that I am trying to get you to supinate the crap out of your forearm so it's training all the major functions of the biceps (elbow flexion and forearm supination).