of course you can use base, concealer, primer, & foundation together.
base, is basically the powder you put on after your foundation.
primer; - theres two different kinds of primer, eye primer, - to help eye makeup stay on longer, and foundation primer, - to help keep foundation loner lasting, and looks flawless on face.
concealer - theres different types of concealer, that's why when you go buy concealers, you see a ones that matches your tone, and a green one. - the green one is to cover up pimples/zits, and the one that matches your tone, is put up under your eyes, to cover your bags, and maybe around your lips,
heres a order of how you can put on makeup.
- moisturizer, primer, concealer, foundation, base, blush/bronzer.
