Open drawer. Pull out all pairs of shorts I own (about 4 pair). Set on chair. Pull out all swim suits I own. Set those on chair. Pull out 8 or 9 shirts (depending on length of trip). Set those on chair. Close drawer. Move to next one. Open it. Pull out 10 pair of underwear (mom always taught me to pack extra
and ten's a nice round number). Pull out about 10 pair of socks too. Also as many bras as I own. Next drawer. Pull out 4 or 5 pairs of pajamas. One pair for every two nights. Next drawer. Grab a big t-shirt for hiking to the pool. All this stuff gets stacked on the chair.
Now. Start rolling everything like beach towels like someone else suggested. I'm an ace suitcase stuffer. You'd be shocked at what I can put into a little suitcase if you give me enough time. Put all those rolled up things in the suitcase.
Next pull out the flip flops. For Disney I mostly wear sneakers so I only need one or 2 pair of flip flops. Those go in the outside pocket of the suitcase.
Toiletries: any shower stuff goes in plastic bags then gets thrown into the top of the suitcase. Toothbrush, razor blades, toothpaste, deoderant, etc gets put in my little toiletry bag than thrown into the suitcase.
Oh, I do generally place a change of clothes, a swim suit, and pair of pj's in my carryon. Also put the retainers and the meds in my carry on.