If he flirts, it means he interested.
Flirting is precisely his way of showing he is interested.
Interested by who?
He would not be flirting if he wants not attracted to you.
Now, what does he want?
Is he saying: "I want to have a relationship with you?"
No, he isn't.
He might in the future.
However, when he starts flirting with you, all he says is:
"I like you and I feel attracted".
See it for what it is.
If you like the idea of flirting with him than go ahead and keep it light.
Now, if you are not interested, you can step back and give him a "no thank you" sign.
If you are excited about connecting with him, the first step is to enjoy the flirt.
Next steps will come after.
Keep it simple and enjoy it for what it is.
If you are truly interested in dating him, simply respond to his flirty moves by teasing him back, giving him attention, establishing eye contact, etc.
All these work wonders on a guy and wakes up his senses.