Well, you might consider doing it in SOME situations, very sparingly... Like when you talk to someone, joke around, and then wink.. that can be kinda cute.. (depending on the context of what you talk about!! eg if you're flirting or joking a bit, and if there is rapport and such..) Or to a girl you like... especially if she's been looking at you, for example.. (and that indicates she might like you) You must also do it in a kind of confident way..
ideally when you're in a good mood.. (And some people practise in front of a mirror haha) Some people can pull it off better than others too, you can see from the situation a bit... (Do they cringe or smile/wink/joke back?)
Not just to everyone everywhere... It's like 'condiment', to be applied sparingly..
Smile and/or nod is safer for 'everyone', yeah...
Just smile is often enough, especially if you're a girl.. If you're a guy also saying hi is nicer, especially if you might want to go further from 'acquaintance' to 'friend' (or more) maybe with that person...
This may also be different in different cultures and environments (eg school vs vacations or work or such, depends on the kind of work too)... I'd expect certain ages to be different too...