cut it into as large as you can get out of each section of garment, that way when you want to use it you have choices in what size. just remove all buttons, zippers, trims, cuffs, collars, open the seams, or cut them right off,and fold the pieces of usable fabric.

Thanks again for the great replies. I will keep them in the biggest part of fabric I can. :)

Just cut the seams out & save all the rest. I wouldn't take the pockets off either cause you can make a cool kids quilt with pockets on them. Kids love them. I use clothing all the time in some of my quilts & have made several memory quilts out of peoples clothing.