At the gym: how to signal that I am socially approachable?

Short Version:

I’m at the gym. How do I passively signal to people that I want them to talk to me? Not romantically, just socially (but I won’t be offended if they misinterpret at first). Most of all, what I’m searching for is the “know-it-all” type, who might enjoy giving me advice on form, motivation, etc.

Making friends is cool too, but not a priority.

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Long Version:

This is a bit of a ramble, I did my best to get the point.

In my experience, different people at my gym have different preferences for how much social interaction they want to have.

Some people just want to be left alone, some people are there for sex/romance, some people want to push each other or make friends or whatever else.

I generally don’t speak unless I’m spoken to because I am terrible at reading this. It seems to me like most people in the gym are also terrible at reading this.

But I want people to talk to me. Any kind of talking is fine, but like I said above, what I’m really looking for is experienced people who like to help out beginners or who like to hear themselves talk.

The most obvious solution is for me to just “be a person,” feel people out and approach those who seem like they might want to socialize. But I don’t like to do that, because a significant percentage of people don’t want to talk. I’m even like that sometimes, and I would be somewhat irritated if approached like that.

I wish there was some kind of t-shirt or something that I could wear, that says something like “The person in this shirt is a beginner. If you see him doing something dumb in the gym, please let him know.”

In case it matters, I am a guy. This makes me extra-reticent to just randomly approach people.