How do you reply to staff in a shop?
They often ask "how are you going?" Or "Hi, how are you"
I like to talk a little bit, but I don't know how I can talk to them well.
What was fun answers or the answers you liked?

See a translation

I think almost everyone answers "How are you?" by saying something like "I'm fine/good/great."

Then you can say some chitchat:
"I'm fine, weather's nice(/bad)today, right?" "Traffic was bad/good though." "I almost slept in today though!"

I worked at a coffee shop and customers who wanted to talk would comment (nicely) to us:
"I'm fine, you seem to be working hard today." Or "Seems busy at the store today!" "You've had a lot of shifts this week!" sort of thing.

That's all very basic but, I could think if more topics maybe...