Fold them in half lengthwise with one leg on top of the other.
Fold the pants in half by bring the hem of the pants up to the waistband. Set the pants aside.
Lay the pajama top out flat.
Fold one sleeve towards the center with about 1/4 of the shirt.
Fold the other sleeve in the same way.
Fold the shirt in half bringing the top of the next up to the bottom of the hem.
Place the pj top on the folded pants.
Fold the waistband one-third of the way towards the center.
Fold the pants the rest of the way into a comact bundle.
Notes
Each pajama piece can be folded separately with these steps.This tutorial works for children's pj's. If the clothes are for young children, you may just fold them in half rather than thirds in the last two steps.