How do I talk to her?

So there's this girl who picks up the mail at my job a few times a week. She seems to be very shy.. she always looks down doesn't make any contact and barely even says hi. Tho I noticed she looked at me a few times and even gave me a smile. Few times she smiled at me and said hi but we never talked. Till recently.

I saw her in the town I live so I asked her if she also lives there, turns out she grew up there. So we had a small talk. That was the only time we really talked.

Few days ago I saw her again at my job, she walked past me, I accidently looked at her so she smiled and said hi to me, I wanted to talk to her again and maybe ask her if she maybe wanted to get a drink or something but I don't have the balls.. We're both 20s. (And i'll admit, i'm shy too.) What can I do?

How do I talk to her?
Post Opinion