First: Pick a partner. It should be someone you’ve already flirted with (and who has flirted back). If you try to play footsie with someone who’s not interested in you, he or she will avoid playing along or tell you to stop. Choose wisely and spare yourself embarrassment.
Second: Be discreet. Footsie is no fun if everyone knows what you’re doing. Make sure you can reach the other person’s feet without tripping over the toes of unwanted spectators. Then quietly slip one of your shoes off (using your other foot to slide the shoe off if necessary).
Third: Initiate contact. Tap or push the other person’s foot lightly and playfully, then pull away. Do it just once and see the reaction. If he or she pulls their feet quickly out of reach, stop. If he or she looks around and says “Who just pushed my foot?” in an annoyed or upset tone, stop. If he or she doesn’t notice/looks confused, make a subtle “above the table” contact. Give a little wink, Or give a cute, playful, or gentle smile. Try not to make the smile apologetic though. They’ll think it was an accident. If you’re lucky though, he or she will be receptive. Then, you should tap them more slowly and linger a bit. Then pull away and wait for him or her to come after your foot.
Fourth: Keep it fun. Footsie should be a gentle and playful way of flirting. Try lightly running run foot up to the other person’s calf and knee, then back down. Massage his or her ankle with the sole of your foot, or lock ankles (twist your ankle around theirs). Make eye contact and smile.
Fifth: Stay stealthy. If you have to stop playing footsie suddenly, throw a wink or a smile at the other person to let them know it’s not their fault. If you’re in a large group, make sure you have your feet back in your shoes and socks in time to get up with everyone else when it’s time to go.
And here is a funny example: