I use the packing cubes from Eagle Creek
My tip: get a "tube cube" or a couple of the smaller 'quarter cubes" or 'half tube'. These are small and rectangular and great for socks, undies, camis, etc. When packing, put these in first, between the ridges formed by the telescoping handle. Great way to use that space & it also levels out your suitcase for the rest of your items or cubes.