honestly their are only a couple of things that would cause me to freak, if i forgot my passport, credit card and cruise documents. Everything else can be replaced.
I am a list maker, i make my list, lay things out in the spare bedroom and check them off the list once they are packed.
Dress clothes get hung in the garment bag, i do use the dry cleaners bags.
I use ziploc type bags for socks and undies, stuff the bag, squish out the air and throw them into any corner of your suitcase.