How do I flirt with guy

Guy is confident around other workmates/girls but seems not so confident around me.

Has done some signs that he likes me like staring/gazing at me for over 10secs and finding out my interests.
Gives me free coffee passes sometime like 3 at a time/extra wifi passes

Works at my local coffee shop, none of his other workmates are like this

If he initiates the How are you or ask if I seen so and so add for tv show I'll answer back and ask him.

But today when he served me I said we both said hi I waited a few sec for him to say how are you then realised he was waiting for me to initiated, but then I go really nervous and started to shake and couldn't get my words.

Then when I sit down I think of all things I wanted to say like have your heard about so and so but then it's to late.

What are some ways I can let him know I do like him/flirt with him and how can I get over being so nervous

I'm not very confident.

Booth late teens also I know that he single