It seems like many skirts selling at the stores these days are mid-thigh length or shorter. Which is a bummer since I'll see a cute skirt at the store and gasp with excitement only to find in disappointment that it's too short. So this is one of two ways I modestify my skirts.
check the hem on the bottom of the dress. is there extra fabric to play with? this one luckily did. see how the hem stitching of the dress is about 3" above the bottom of the skirt?
unpick the bottom of the dress all the way around.
unfold the extra fabric down.
fold it twice, then hem the bottom of the skirt.
this is what the finished product will look like.
viola! it's 3" inches longer now!
FYI: this will not work on all skirts, you'll have to flip the skirt over and check the hem to see if there's any extra fabric to lengthen.