I would like to recognize signs that someone wants to be approached and signs that someone doesn't want to be approached

I will list mine
wants to be approached: make-up, dressed well, you can tell she took a lot of time making herself look good, no earphones in ears, walks slow, looks around
Please don't talk to me: looks like shit, walks fast, earphones in ear, looks straight ahead

are these right?
can you list more?

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I have not failed 10,000 times. I've just found 10,000 ways that won't work. - Edison

It really doesn't matter. You can interrupt sets and take it over.

Very good list.
A PUA who opens indiscriminately, ignoring your list, will get a lot of rejection and ignoring. You have a good idea to minimize the number of approaches to taken/not-open girls.
One sign she is ready to be approached is she's sitting at the bar, but that's easy.
I'll share this: i ignore all those signs. In my mind, they are all waiting for a hot stud like me to talk to them. It exposes me to a lot of rejection but I just keep going. Not every girl will like you at that particular moment you meet. A lot of them might even make a snap judgment which they later regret. Even girls don't deal with as many approaches as a PUA; we are more experienced than they are so cut them a little slack sometimes. They're all learning as they go too.

I agree with the above two posters.

There isn't really a sign to want to be approached. I saw girls looking pissed off as hell before I approach them, after approaching, they gave me the biggest smile.

Saw some girls smiling and looking like they are having fun, when I approach them, they just back face me.

Just approach. Open first and calibrate later, you just really never know until you open.

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