(1) plastic bags - I use the small clear trash liner that comes in a roll so I fold them neatly to fit in the hanging organizer and it takes up no space at all, but grocery bags will do too.
(2) S-hooks - I usually don't need them now that I have the hanging organizer but in case you have the first row you may need them so you can hang things off the front pocket. They are small enough to bring and very helpful when you do need them.
(3) wet nap or baby wipe or pretty much any anti-bacteria wipes will do. If you have the big value pack cleaning wipe at home, just grab a few and put them in ziplock bag to take with you.
(4) hanging organizer - I bought this one but pretty much any hanging organizer will do. Just try to get a soft one that you can fold and put away easily when you don't need it.
Trash Bag on seat back coat hook
It is very handy when you have trash you want to get rid of and a flight attendant is not nearby to take the trash from you. Do you know there are coat hooks on the side of the back seat? There should be 2 coat hooks on each side of the middle seat, and one for the seat on the isle or window. I use that to hang a plastic bag for trash. On some flight that comes with a blanket in a plastic bag, if the bag is heavy duty enough, like the ones I have seen on Eva air, I would carefully ripped open the bag from the top and reuse that as a plastic trash bag.
No more using seat back pockets
Do you know how much germs are on the airplane? Especially the seat back pocket where people put all sorts of stuff including tissues after blowing their nose. Ever since I found out how gross the seat back pockets are, I don't touch anything in there. That's why I bought this hanging organizer with velcro strap so I can strap to the "arms" of the fold down tray table. And it hold a bunch of other stuff like your glasses, cell phone, headphone, water bottle, hand lotion, paper napkins, tissue and any other knick knacks you have.It depends on your flight attendants but some may not let you put the organizer on before take off. The good thing is this one I have I can unhook the straps so I don't have to take the velcro straps off the tray arms.