Small MAC Buffer Brush (maccosmetics.com)
Brush Description - For blending powder, cream or liquid-based products or for removing excess powder. This is a small, full, circular brush with a flattened tip. It can be used to blend and polish.
Okay....so you put on foundation regularly...and the parts you want to "show through" more you buff with this brush by moving in a light sweeping motion to get excess off....then go in a circular motion to blend the area in again after taking off the excess. Usually I do it to cheeks, nose and a bit on the T-zone-forehead...then my freckles like Mischas show through....( click on my name and on my profile pic you can see on my cheeks I buffed it enough that you can see my freckles...good thing I saved that quick pic because this question came up before
Even though my eyeshadow is still unblended there
)
Mac Fix + (maccosmetics.com)
Product Description- Liquid refreshment for the skin. A vitamin-rich pick-up for the skin - and a perfect finishing "fix" for makeup. Spray it on. Sets makeup. Wakes up the skin! Alcohol-free. Herb-infused. Shot with caffeine. One smart tonic. For a fresh finish to a look, apply over moisturizer and under foundation. Use over powder for a soft "set" finish. Non-irritating: skin calming. Botanically formulated. Naturally aromatic. Skin-quenching. Does the skin good. Let the skin drink it up!
I mentioned that I use this after I've done the buffing and put on my blush. This "sets" make up and gives it a softer finish and also its just pleasant to the skin
I don't know if I answered your question on the technique enough...but thats about all there is to it...just play around with it.