Sometimes I have given compliments to strangers. But it is a risky move as you can come out as creepy. I think the safest choice is to compliment older people. Also complimenting the pets or the bikes works alright.
Not creepy: "Nice watch!"
Creepy: "Nice waist belt!"
Very creepy: "Nice eyes!"
Just you know, don't be weird.
- They are expecting people to notice it.
- It's not a trait they were randomly born with, but rather is something they decided to do.
The point here is that you don't know if they're a loud-and-in-charge extrovert or a shy high-anxiety introvert until you talk to them.