I suck at this but I'm getting better at just smiling and saying "Thank you!" or "you look great too!"
But what do you say if the person who says "OMG you look great!" doesn't look great.... I feel awful but I don't know how else to say this! I saw a friend I hadn't seen in about 6 months and she looked like she'd gained a LOT of weight in that time. I didn't want to say "So do you!" because I knew she'd call my BS but I felt like a jerk being like "Thanks!" What do you say?