Use a contact case as storage 1
Have any extra contact cases lying around? Use them as storage for your cream concealers or lipglosses!
Use solid conditioner 2
I tend to use a lot of shampoo and conditioner so using those travel-sized bottles never cuts it for me. Instead, try packing a solid shampoo and conditioner (like this one by Lush) that won't get all over your things, but takes up less space than the liquid stuff in a bottle.
Pack makeup brushes in eyeglass cases 3
If you don't have a brush holder or don't want to carry a bulky makeup, store your essential brushes in an eyeglass or sunglass case. It'll save space and you won't have to dig through your bag to look for them.