If you're starting out with training, the general recommendation is to do big compound exercises (if you're powerlifting things like barbell squat, barbell dead

If you're starting out with training, the general recommendation is to do big compound exercises (if you're powerlifting things like barbell squat, barbell deadlift, barbell bench press; if you're doing calisthenics things like push-ups, bodyweight squats, etc.). Once you're able to go through the motions of those, it's possible to identify which part of the exercise you're not doing so hot at, e.g. if you were doing bench press and you find that your shoulder gives out sooner than your chest, you would want to employ some shoulder exercises to help out.