The Details: This bag is made to hang, so I keep it in the closet or on a door or towel rack. It has four zip compartments and a little elasticated slot where I store my toothbrush. The see-through compartments are crucial because I can locate everything quickly! As you can see from the photos, I usually put skincare products at the top, random essentials (deodorant, toothpaste, lotion, vitamins etc.) in the second pouch, makeup and hair bands in the third and hairbrush, cotton rounds and eye makeup remover at the bottom. It doesn't hold absolutely everything I bring with me (hair products and soaps go in another bag, for instance), but it has a lot of space and keeps all the little odds and ends organized. The hook is extremely sturdy, so the bag can sustain a lot of weight. The bag rolls up into a little bundle that you can tie with the attached ribbon. From how small it becomes when folded, you'd never guess how much stuff can fit inside!
Where to find one: My bag was from Cath Kidston, and you can purchase a similar model here. Luckily I got mine on sale; at £28, it's a little pricey, but I still think it's worth it. If you want a smaller, cheaper and less girly alternative, you can check out this one from Muji. You can also find many great and affordable options on Amazon -- just search for "hanging wash bag" or "roll-up toiletries bag." I'm actually surprised that more companies don't make bags like this, but if you shop around, you'll find a good one.
This bag has preserved my sanity through many moves and trips, and I highly recommend it if you travel a lot. It's also great if you live in a dorm or small apartment and are short on space. Hope this is helpful, and if you have any travel organization tips, I'd love to hear about them in the comments below!