Blending a Foundation can be a challenge for some people and it really does take time to get the perfect end result your looking for. There are two ways you can use to blend foundation in.
1.using a brush
2.using fingers
Brushes
First things first with a brush you could either use a Foundation Brush or a stippling brush..the difference between a stippling and a foundation brush is that a stippling brush is used to create a air brushed,high definition look, where as, a foundation brush will pick up a lot of product and glide over the skin (bit like a paint brush on a canvas) A stippling brush does take longer to use though.
Pour the Desired Amount of the product on the back of your hand and dab the brush in,start from the middle of your face (cause thats where you will need the most coverage) and then work outwards .
Fingers
Using your fingers is a good way for a more quicker application, pour the desired amount onto the back of your hand, then let the product warm up between your finger (this makes the product go warm and it will blend in easier with your skin tone) again,start from the middle of your face and work outwards.
Remembering to blend it down your neck and into your hair line! If you decided to use a more darker colour then do your ears aswell.