A healthy diet is essential to healthy skin.But until you get there, here's how to fake it. With oil! I highly recommend you moisturize with oil. Apply it a few drops to wet skin or with wet fingers to easily apply a very small amount. And then, you get a dab more oil on a couple of fingers and pat at the top of your cheekbones, away from your nose. Shine on top of your cheekbones looks fresh, dewy and young. Shine near or on your nose and forehead looks greasy. You can do this on top of your makeup.
Ideally, you want to use a fresh, quality, properly stored Safflower or Grapeseed Oil, but if you have a good olive oil, hemp seed, camellia, almond or other oil on had, feel free. The reason for the other oil recommendations is that they are high in linoleic acid, a major and vital component of sebum that does what it is supposed to do, protect and make your skin glow. Rather than look greasy and clog pores. A deficiency in linoleic acid in sebum leads to a variety of skin problems including acne. And the sebum in people with skin problems has been found to be deficient. When you apply it topically it spreads throughout your sebaceous glands, changing your lipid makeup. This actually applies to all mammals, so if you have a dog with itchy sensitive skin, try it on him too. I do, and it has worked wonders. Examples of skin problems affected by a deficiency in linoleic acid include acne, eczema, psoriasis, keratosis pilares, hypersensitivity to allergens, and dry itchy sensitive skin of all types--aka dermatitis.
The reason I stress high quality and proper storage is that most plant oils are high in polyunsaturated fats which are very prone to turning rancid. And the average oil in the average supermarket is likely already going rancid. (Careful with them in your diet as well!). A quality oil should come in a dark bottle or tin. If the manufacturer of the oil doesn't put it in a dark bottle, they don't care about the quality of their product. Buy it from someplace where there is a high turnover. Or where it's kept refrigerated, ideally in the dark. And once you get it, put a few ounces in a dark bottle for your regular use and keep the rest in the refrigerator.
You can find all my research on the role of linoleic acid in acne here: http://www.acne.org/messageboard/topic/314390-acne-prone-skinsebum-deficient-in-linoleic-acid-possible-topical-solution/