Suitcase packing tips

I love these tips from a suitcase-packing ninja, aka Heather Poole, a flight attendant from Los Angeles. I've been rolling my own (clothes, that is) for a long time, but I like the tip about what to do with dressy items. My problem is that, once I've squished in all the necessaries, if there's an atom of extra space, I stuff in something else. Then another little item, until I end up having to sit on the suitcase anyway. I must have been a squirrel in another life.