I had posted this some time ago...took me awhile to find it. Don't know if it will help you or not.
I hate spending time and energy looking for stuff while on vacation, so I pack a port day bag at home. Then, I can just drop it into whatever bag or backpack I take into port. I buy or create as many mini-sized things beforehand. The port bag has:
Insect repellant towelettes
Mini toilet paper pack
Small first aid kit with bandaids and alcohol prep packs
Small supply of my most critical medications
Water bottle that I fill up with juice from the Lido
Disposable rainproof poncho
Rubber bands for getting my longish hair up off my neck
I'm sure that everyone has different things they might put into this, but these are my basics. OH NO...I almost forgot...my camera!