METHOD #3: Full Coverage
EDIT: 5/11/2015 -- Thanks for all of the continued interest in this series! For more recent tips and tricks on using this product, check out my Kevyn Aucoin tag.
I'm not opposed to boasting about KA SSE's opacity--in fact, I do it often--but it's extremely rare for me to wear it as a full-coverage foundation. I don't find most full-coverage foundations very flattering on my skin, it essentially blanks out my face, and I have to use an extra product to make this method work: a primer. Of course, if you wanted to try this method, you could use any primer you wanted, but the most unique primer I've found, and the one that seems to work best with this foundation, is...
...the Kevyn Aucoin Sensual Skin Primer. Predictable but true! It's notoriously expensive for a tiny product; as you can see here, the tube is even smaller than some mascara tubes. But you only need one pump of product to do your entire face, and that's a surprisingly teeny amount of product. Also, if this method ended up working perfectly for you, consider the primer your "regular repurchase" item--many people repurchase their foundation three or four times a year, but because the actual KA SSE lasts for so long, you'd only need to replace it every 2 years or so and would instead repurchase the primer. And again, you can use a different, less expensive primer if it suits you better. This is just the product that seems to work best for me.
I start with by pumping one pump of the primer on to a finger tip. Then I use another finger to pick up some of the primer, which I rub in to my face section by section. What I like about this primer is that it has a creamy, almost moisturizing feel, and it smooths my skin out without feeling slippery or silicone-y. The perfect surface for a thick foundation! (NOTE: Some people also mix the Kevyn Aucoin primer directly in to a dab of the Sensual Skin Enhancer and apply it that way, but I find that this sort of "direct mixture" doesn't spread over my skin as well. Weird, huh?)
Once I've blotted on the foundation, I start buffing it in with a soft, dense brush; my personal favorite is the Real Techniques Expert Face Brush. I usually do some sweeping motions to sort of "disturb" the product and keep it from settling on my face as a bunch of dots, then I do small, circular buffing motions to really work it in and make it look more "natural," so to speak. If my skin is exceptionally sensitive, I'll work in smaller sections and sort of "roll" the product in to my skin with my fingers.
I apply a smidge more KA SSE to my undereyes using my fingers, as that part of the face is uber-delicate. The result is this: your entire face is blanked out. Actually, you can get even more coverage than this by using a hair more product and buffing a bit less, but anything more than this is a bit too much for my face. I never contour, as my face is quite thin and can look borderline horsey, but others may prefer to put some "shape" back in to their face after it's been blanked out like this. I do set my skin with a sheer powder and a bit of setting spray when I use this method, but that's because I'm terrified of full-coverage foundations moving and revealing my makeup secrets to the world.
And that's it! That's how I apply the Kevyn Aucoin Sensual Skin Enhancer. There are tons of other ways to apply this incredibly pigmented, versatile product, so I highly recommend that you do some experimenting of your own and find what works best for you. In the meantime, I hope these mini-tutorials have been helpful. :)