Summarize the following:
A lot of people choose to apply lemon juice overnight, incorporating it into their nightly face-washing routine. If you don't want to leave the lemon juice on overnight, try applying it right after you wash your face in the morning. Make sure your face is completely dry and moisturized before proceeding. Leave the Q-tip in the lemon wedge for a couple seconds for good measure. You should feel a bit of tingling on your skin, but it shouldn't hurt. Re-saturate the Q-tip in the lemon wedge as necessary. Only target your problem areas. How long you choose to leave the lemon juice on your skin probably depends on two things — whether you're targeting scars or acne, and how sensitive your skin is:   Scars or acne? If you're trying to treat scars only, you have a little bit more leeway, because you're using the lemon juice to lighten skin, not heal acne. In this case, you can afford to leave it on for several hours to overnight. If you're treating acne, try leaving it on for less time.  Sensitive skin or not? People with sensitive skin have a harder time leaving lemon juice on for longer periods. If your skin is very sensitive, reddens easily, or generally doesn't behave, stick with a couple hours at first before experimenting with longer durations. Apply the lemon juice every 1 - 3 days for a period of several weeks for best results. If lemon juice doesn't work, try seeing a dermatologist or consult other sources on treating acne fast and naturally.

Summary:
Wash or exfoliate your face to remove oil, dirt, and sweat. Take a Q-tip or cotton swab and saturate it in a wedge of fresh lemon. Use the Q-tip to dab at only acne and acne scars. Cover your lemon with plastic wrap and wait for a period of 30 minutes to overnight before washing off. Wash your face to remove any excess lemon juice.