Don't stop on the neck. Move down and trail your tongue down as you tease both his sense of touch and sense of excitement.
I discovered early in my relationship with my fiance that if I licked, sucked, and made like I was eating something and I held my lips right at her ear, she would squirm and writhe. It wasn't that she was trying to get away, but rather I was tickling some place without even touching it physically. Want more ideas? See the source section