How do you flirt physically with confidence?

A couple of things off the top of my head:

-When he makes a funny joke (genuinely funny!) playfully touch his arm while you're laughing.
-Paint your nails a new color and offer up your hand to him and ask if he likes them.
-If he holds a door open for you (he should be doing this!), then brush your hand against his lower back as you walk past him to enter through the door.
-If you're out at night and it's cold, tell him you're cold. He should get the hint to either give you his coat, or put his arm around you to keep you warm.
-Tell him your shoulders are sore from doing XYZ, and maybe he'll offer to rub them for you.

There's no guide on how to do it. I suggest watching a movie together and slowly lean towards him till you finally touch. Once you get to that point, it will feel more natural.