If you have wool kilts, the opinion varies...

I hang mine in my closet (on 3 clip hangers) and have some bags of lavendar in there to keep any POTENTIAL moths away (we don't get too many moths here... *knocks on wood*).

If you only wear it once in a long while, we suggest taking an old pillow case and poking a hole thru the closed end. Hang the kilt inside it (like a cover) with a small bag of lavendar. The cloth (as opposed to plastic) allows the wool to "breathe" and air to circulate. The Lavendar bag smells nice (MUCH better than moth balls) and keeps moths away.

If you have a cedar closet, you can hang it in there, without the bag or lavendar.

If you have a cedar chest, you can lay it flat and gently fold it and put it in there. The only problem is that you'll probably have to steam the creases out when you want to wear it.

If you have NON WOOL kilts (acrylic, cotton, poly blends, PV... etc), you can just hang them in the closet.