Tips on tournes!

Start with a medium-size potato.  Peel it, and cut into quarters, and cut off the ends so they're flat.

Use a standard paring knife, or, if you have one, a paring knife with a curved blade, or "bird's beak."

You may find it easiest to carve the potato into a small football shape first.

Then, begin carving it into seven equal sides.  Some chefs prefer to cut each side, and then to begin evening the shape.  Try each method until one "feels right" to you.

Try carving in profile, rather than having the side you're carving pointed towards your face.  Cutting "in profile" allows you to have a background that highlights the product (it's easier to see).

(Be careful!  This is one of the few knife cuts you make toward yourself, rather than away!)

When your sides are even, cut off the tapered end of your little "football."  A classic tourne should be able to balance on one end. 

Why?  Because the chef said so.