Steve:
His neck. He blushes like crazy and makes this adorable face!

Clint:
Forehead. You just like to.

Bucky:
Left arm. He hates it but you kiss it to show you love all of him!

Loki:
His chest. Right were his heart is. Your short compared to him and you love how big his heart is!

Thor:
Jawline. Let's just say..things escalate quickly.

Tony:
Lips. Starts sweet but things get heated!

Bruce:
Cheeks. Cute and innocent like him.

Pietro:
Between shoulders. You hug him from behind and kiss.