I have a habit of overthinking things and seeing things which aren't there, but I can't help feel there's potentially something more to it all. However I also made a dickhead of myself. I'll explain

>Go to same store regularly
>New girl starts there
>I somehow get in her way every single time I go in
>This sort of becomes a running joke
>Now every time I go in she sees me and laughs, in a nice polite way
>She did the same thing today but she was also serving on the register
>Go up to the counter with my item
>She seems to be laughing when she sees me coming over
>Then she notices I have an item and immediately stops
>It felt like she tried to make some kind of small talk today (we've never once spoken properly)
>Like a complete autist I ignored what she said and asked her the most retarded question I possibly could
>She kept her professional demeanor and I could already tell she thought I was mentally handicapped
>I did a 360 and walked right the fuck out

I even said to myself next time no one was in I would initiate some kind of small talk with her myself. Today was that day, there was only me and her. Literally just before I went to the counter two other workers came in and about six other people. It's only a small place so it made me hot and flustered bros.

tl;dr How do I strike up some kind of conversation without looking like a complete fucking retard especially after what happened today?