When we decide to go on a vacation... here is what I do.
take out the suit cases and air them out. As they air out...
I lay out the clothes and stuff on the guest bed.
Every day I look at the clothes etc... and ask myself... " Do I really Want That / Need that ? " if we don't need it, its get put back away in the walk in. And the suitcase suddenly looks lighter.
Now when it comes time for actual packing, my husband does it. A Navy Man. ( Viet Nam) If you can pack a Sea Bag and not have wrinkles... you can pack a suitcase without wrinkles. And he does!
( The Navy must have a class as of how you pack one.)