I separated one last fall and took a good chunk of the mother (probably too much). They both made it fine, but it would be nice if someone had some pics or a tutorial on the subject?

If you use a straight shovel, you'll have greater success.

Cut on a angle this way, (mother / pup) toward the mother.Some people just cut straight up and down and that works too!!! I prefer to cut on the angle. Diana55

I always remove my Pups in the Fall and I always wait until they are at least 2 feet tall. This gives them a better chance. Diana55

Check out this thread, "Time to separate the pups for the Spring":
http://www.bananas.org/showthread.php?t=1814

It shows step by step the separating of a pup from the mother plant.

The pups being that close makes it easy, you have the mother plant to use as the fulcrum when you're wedging/prying the pup off.

Here is a link that might be useful: Time to separate the pups for the Spring

You don't really need a piece of the parent corm - but you need to get the whole corm of the pup. Each variety is different. Some, if you cut straight down, that is fine. Some you need to angle under the parent corm a little bit.
You will have to experiment a little. Start by taking one that is 12-16" tall. If it has good root development, then that was a good size. If not, pot it up and it will look terrible for a while but will almost surely survive and grow. If there weren't many roots, wait till the next one is a little taller, say 2' and try again. I have had pups that were 3 inches tall that had so many roots that they barely fit in a 15 gallon pot. I have had 3-4 feet tall pups that would fit in a one gallon pot, because there still wasn't any root development. Experiment and get to know your variety.

Also, the first pups from a Tissue Cultured plant tend to have little or no root development till they are more than 3' tall, but the second generation is more normal.