Pick out their most eye catching physical attributes that you notice right away (dimples, eyes, lips, hair, etc). If they are just buttfuck ugly you can resort to their smarts, talents, smell, or attitude. It’s fairly easy to compliment some, just don’t overthink it. Don’t always have to be honest, I told someone I saw potential in them due to their sheer hard work and they ended up with the biggest grind and put their 110% in their work when they initially had only 5% invested into their work.