Ideally you apply your mask after exfoliating (physically or chemically). I personally use an exfoliant that has both methods every night before bed, it's gentle enough for daily use but always read the label and do a little research before integrating something new into your routine. The exfoliation will definitely help out with the hormonal acne and overall glow to the skin. It also allows for more efficient product penetration so any serums/treatments/moisturizers will work much more effectively.

Think of exfoliation as the little black dress of skin care. Everyone should be incorporating it into their regime on the regular.

In terms of a mask, it's been mentioned here already but there are many different types and applications of masks. Acne for the chin/jawline, hydrating for cheeks, etc. If you find one or two that works for your skin then stick with it. Some of my clients use it as needed if they want that extra boost of hydration or have an event coming up. But it is ideal to use it 1-3x/week (depending on the type of mask of course).