Instead of smiling when placing your blush on your cheeks, try not to smile. You see when you smile, the apples of your cheeks elevate. So when you place your blush on the apples of your cheeks while smiling, the blush will then pull the color down your cheeks when you stop smiling. Creating an illusion of lower cheekbones. And we don't want that.
TIP: apply blush without smiling.
Your blush should also complement your face shape. When your face is more elongated or let's say more like an oblong, your blush should be more horizontally / parallel to the ground. This creates the illusion of less longer face shape. So you brush it from the apples of your cheeks to your ears. Unlike when your face is rounder or more circular, your blush should make your face look slimer & longer. So you brush it from the apples of your cheeks to your temples. Illusion is what you need to maximize the effect of your blush.