Questions: Flirting

I've made the mistake of seeing a girl I like but don't say anything and then she's gone. I don't want to run , raise my voice in desperation, and say "wait a second, can I talk to you? "

I feel thats startling and she has no clue who I am. Still its better to try than not but I don't know how to go about it.

There’s a girl at my job who’s really cute
I introduced myself to her Awhile back
Then today I saw her & decided to Talk a bit more.

We were just getting to know Each other.
Thing is, we work on completely different floors.
She works upstairs, I work downstairs.
I always sit upstairs for awhile before I Clock in, So I see her all the time.

Anyway, She asked why I sat upstairs if i worked downstairs. I Told her because it’s warm upstairs & because I get a chance to see her...

Was that creepy?
She just laughed & Said
“So you Come up here watch me when I walk by?”
I said yeah
& We started talking about something else..

Should I not have said that?

I personally am indirect unless I'm getting some clear signs from the other person that they are interested but even then I still beat around the bush...

I’ll be walking and feeling like someone’s staring at me so I look around and often catch them looking at me first. I look away. Can’t smile due to face masks.

Girls, do you often just stare at strangers in Walmart, for example