Toiletries are odd shapes and sizes and often feel really miscellaneous. So always try to go for travel-sized versions to save space. Pack a comb instead of a hairbrush, and liquids in 100ml refillable bottles.
And when it comes to liquids, keep them together in a leak-proof bag so that they don’t spill all over clothes and electronics, and so that you easily can pull them out when you go through security.
There are toiletries bags that will hold all of the toiletry items, with a convenient hook so you can hang it on a door or towel rack at every stop. They’re light weighted and most of them are water repellant, so you don’t have to worry about your shampoo leaking onto the rest of your gear.