“Foundation should be an area rug not carpeting.” The best tip I learned as a makeup artist regarding foundation, was not to cover the entire face. Only apply foundation in areas where you want to cover up redness or other flaws, and blend out to other areas where the skin looks good. The easiest way to do this is start with the center.

The quickest way to apply foundation is with a brush. I used to love using flat brushes but ever since I discovered Marc Jacobs Beauty The Face II - Sculpting Foundation Brush No. 2, I never went back to flat brushes (unless it was the only clean brush). I love using this with the
Diorskin Airflash Spray Foundation; just spray it on your brush and blend away in circular motions

Your hands are also a great tool when applying foundation. The natural warmth of your body temperature helps the foundation do its job. I usually do this with the lighter foundations, like 
Chanel Vitalumiere Aqua Foundation SPF 15, because they are easier to wash off than the heavier thick products.

My favorite tool for foundation used to be a triangular sponge. I loved using these because they get in every little corner, like around the nose or under the eyes. What I hated about them was that they soaked up all my products. I stopped using these when I discovered the Beauty Blender. I just wet the blender, apply a few drops of foundation on the back of my hand and pick it up with the blender. Next, I bounce it off on my face going all over with the round side. I really use this with any tinted moisturizer, foundation, concealer or even cream blush. 

Aline Agopian