One way to cut down on the number of things you take is to find items that will do double duty. As for cleaning your face, find a foaming oil so you don't need to take both the oil and the foaming cleaner. If you aren't into cleaning your face with oil and a foaming cleanser, look for a wipe that will both clean and exfoliate your face. These wipes or towelettes are great for cleaning and exfoliating and some will also brighten your skin at the same time so read packs carefully.
Instead of adding a blush, bronzer, and highlighter to your makeup bag, find a palette that combines all three into one container so you have everything you need to contour and highlight at the same time. There are also small boxes with powders designed to fill in your brows and wax to make eye brows perfect. In addition, look for a stick that has both eye liner and shadow. A good one will allow you to make either thin or thick lines along the lashes while the shadow end will easily apply shadow without needing a brush.
If you can't find one of those, eyeliner pencils can be used to create the line and then applied on the eyelid and smudged to get an eyeshadow look but a creamier eyeliner is better for this. Pack a few different shades to mix and match liners and shadows. To fully finish off the look, get your hands on a two step mascara that has primer on one side and mascara on the other side.
It is also possible to use a nice creme blush both on your cheeks and to add a bit of color to your lips. Furthermore, there are lip liners out there that will allow you to line the lip while filling it in so it looks like you are wearing lipstick. Want your nails to match your lips? Go for the strips of nail polish stickers so all you have to do is apply them. The stickers can be used for the full nail or just the tips for a French manicure style. You don't need to take bottles which can break or spill. In addition, they are extremely light and don't take up much weight or space.
Check out a BB cream because it can replace your foundation, sunscreen, and a moisturizer inside your makeup bag. Using a BB cream means one tube or bottle instead of three so fewer bottles means less weight. I am picky about my sunscreen and prefer to take a small bottle of my preferred brand but I like a nice tinted moisturizer so I get the hydrating power of moisturizer with a bit of color.
Although you can use certain types of makeup in other ways it is not always the best suggestion. Makeup such as lip liner can be used to fill in the eyebrow while concealer can be used as an eyeshadow primer or to contour. Eyeshadow can be used on the lips or as a highlighter. Lipstick can double up as blush, to correct color, and if it is in liquid form, it can double as eyeliner.
I prefer the products meant to be used as intended but I also need to know where to find all of the alternatives so I can reduce the number of things I carry with me when I travel. Let me know what you think, I'd love to hear.