My method of application for diffuse thinning and long hair (4").
I suffer from thinning from one temple to the other - looks a bit like a "horse shoe".
-I use half a cap.
-Water in the hand basin to cool the finger(s).
-Dry finger.
-Apply foam just to the "tip of finger" for diffuse areas. Other hand using mirror.
-Balder areas like my temples you can hit harder.
-Even apply it to the front hairline just to see the effects - if any.