I am a MAC addict. I use MAC everything. I have Bare Essentuals and I have been using that lately. Just doing the Natural look.
MAC, however, has a product called paint pot. These are awesome shadow primers. They come in a variety of colors and hold your shadow in place and prevent it from creasing. I use it everytime I apply eyeshadow.
Also, a makeup artist told me this once and I couldn't agree more. Your eyebrows are the curtains to your face. A brow brush and brow powder will define them and make your face look great.
