The card stock on these things is often slightly glossy, which means it's not a great surface for my Prismacolor markers.. So to avoid smudging and splotches, I lay down all my light colors first. I put down some flesh tones, then light grays, eye color, some shading, blonde hair, whatever else. I let these marker colors dry completely before I add any inks.. I used to ink and then add colors, but I've found it's much safer to go this route.. It's a little trickier and takes more practice, but ultimately it saves me a lot of headaches, especially on these slightly glossy cards. (If you're looking to get some blank card stock for artists to draw on, I highly recommend going for matte surfaces and NOT glossy.) This Valkyrie one wasn't too bad.. Like I said, it was only slightly glossy, so I didn't have any huge problems.
After those markers dry, I grab a Faber-Castell Pitt brush pen and do my inks. I'll add some darker marker colors in, too.. maybe do a little blending (ie. grab a gray or a goldenrod type color and add some extra shading) - whatever makes it look okay. And then for this one, after my inks dried, I grabbed a Bic Wite-Out pen and put some random "snowflakes" on there.. Those Wite-Out pens can be handy.. I screwed up her left eye a bit while inking and ended up using the Wite-Out to cover my mistake, then go over it again with pen.. And you can't even tell now. :)
And of course, you always gotta be sure the card is dry before you (a) scan it in, and (b) put it in a plastic sleeve to mail it off to its new home.