Have her lay on her back with a small pillow or rolled up blanket under her ankles. Her feet should be as close to the edge of the bed as possible and the pillow should have her heels up off the mattress. Get some decent lotion. Something creamy that won't absorb into her skin too fast but at the same time won't get too slippery. Trial and error there.
Work one foot at a time using a variety of motions. Here are a few that I use:
Facing the bottoms of her feet, take both of your thumbs, place them on the center of her heel, wrap your remaining fingers around her foot. Slide your thumbs up. On the first pass leave the heel and got up the left side of her foot, then up the middle, then the right.
Wrap both hands around the foot making contact all the way around. Use lots of lube and working from heel to toes pull your hands up while applying gentle pressure, think of it like squeezing the blood from her heel up to her toes. Do that several times.
Wrap your hands around her calfs and with plenty of lube, pull your hands down her leg holding gentle pressure aourn the leg. When you get to her ankle apply gentle thumb pressure around that little ankle knob. Working the leg and then the foot seems to work nicely.
Dont forget the toes! With the thumb and index finger, gently squeeze the base of her toe at the ball of her foot and slowly work your way up the toe. Do that on each toe.
Lather the toes up with a bunch of lube. Put your hand above the toe, grasp it with your thumb and index finger and pull up, imagine the toes are very small carrots that you are trying to pull from the ground (if you dislocate her toe you will not get laid so do it gently). Gentle pulling on the toes seems to be very pleasureable.
Whatever you do DON'T TICKLE HER FEET! It ruins the relaxation of the massage and most women will hate it if you tickle them during the massage.
Key here is to move rhythmically from bottom to top or vice versa. Use gentle pressure. Use lube.