Whether you peel the potatoes or not is up to you (if you don't peel them, be sure to scrub them clean). I like to cut out eyes and any dark spots, but I like a pristine looking fry.
Peeled or not, the cut is rather key when making French fries. If you have a mandoline, this is the time to break it out and use it. If not, cut each potato in half the long way, lay the cut side flat on the cutting surface and cut into 1/2-inch to 1/4-inch slices. Stack these slices and cut into the same width sticks. Repeat with remaining potatoes.
