Cut the lemon, add a drop of honey, and rub it directly on your clean face in a circular motion. Leave on as long as possible. Honey helps lessen the stinging, and I think it works better this way.
I have severe cystic acne, and this has taken the "topical" stuff away. This was the only treatment my skin had responded well to since antibiotics (which I refused to keep taking). I was still getting some cysts, but my skin had not felt this smooth in seven years. I won't say it's a cure, but I have been on "The Whole 30" for 13 days now, which seems to be curing the cystic stuff. I've found changing my diet to be the best choice I've made in curing my acne.
I will continue to use this mask and hope it lightens the scars, which are now my biggest problem. (It has lightened them some, but it's a slow process).
My routine, if you're curious:
Eat a Whole 30 diet
Wash my face gently with warm water, a wash cloth, and organic soap nightly(something natural with the fewest ingredients possible)
lemon&honey mask nightly
moisturize with pure aloe vera (from the plant) daily