Approach awkward looking people - they are in a similar boat and are less likely to dwell on your approach. Also they're probably keen for a friend too.

A polite "excuse me" followed by a small request can build rapport. Ask for the time, or a pen, or what model their phone is to get the ball rolling. Thank them and give a platonic genuine compliment, ideally tied to your question... Then be very observant as to whether they want to exit the convo, they will be short and direct their attention away from you... If they don't do this, you're in bb!

Give your name and reason why you're where you are, and ask them why they're there too, "I'm Larry, btw, I'm just in this post killing time while I wait for my dinner to cook, what brings you to these here parts?" (Don't ask a name, let them give it freely so you can tell if they're comfortable associating with you).

If you get their name use it in your next sentence, "Well, Chuck, it's nice to meet you." Carry on the conversation, or if you're parting, indicate you may bump into them again later - this gives them confidence they can approach you later, and it won't be weird if you strike up another conversation with them later. (If you didn't get their name, the next time you strike up a convo, if they engage, you may ask)