I have a "Disney bin", which contains all my go-to items to bring on our trips other than clothes, shoes, my make-up, autograph book, mousekeeping tip envelopes, new itinerary, and sunscreen. The bin contains things like misting fans, pop-up hamper, ziploc bags, Frogg Togg towels, band-aids, Disney light-up toys/lanyard, pennies for pressing, trading pins and lanyards, over-the-door storage thing, ponchos, soft soap, etc. This has cut down how far in advance I pull out the luggage to start the packing process.
I usually start putting things together in the luggage about two weeks out. I then keep a checklist with the luggage and mark things off as they're packed. This prevents me from second guessing myself about what's made it into the suitcase.
The bin started out due to laziness. I hadn't totally put everything away after a trip and ended up throwing it together in the bin.