I have never heard of foot sex, but of course the feet are highly erogenous zones for both men and women. Start by washing your lover’s feet. Dry them and apply a light lotion or massage oil. This simple procedure is a delight for any man or woman. To increase the stimulation try sucking on each other’s toes, which is sure to drive your partner wild and increase their sexual desire strongly. The toes may be used to stimulate the vagina and may be inserted inside the vagina as well. For example you might be seated in a restaurant at a table with a draped table cloth hanging over the sides. Remove your shoe  and be sure your female partner is not wearing any underpants. Discreetly raise your toes to come into contact with her moist petals and stick your big toe inside her while you carry on a (reasonably) normal conversation and enjoy your meal.