Which muscles should I train first?
One of the most common 'lifter' injuries in the gym is called Rotator Cuff Injury. The Rotator Cuff is a group of tendons and muscles around the shoulder joint. There are many potential causes for Rotator Cuff Injury, one of them is due to muscle imbalance. With the right exercises, this imbalance issue can be resolved. This is a good example of how important balanced training is for our workouts, to prevent setbacks.
The best way to prioritise a weak area is to train it when you feel fresh, and strongest. At the beginning of the workout week is usually best. If for example you feel your shoulders are underdeveloped, then train these first, on the first day of each week of your training plan.