Let’s say that you two just met. Be kind to him, smile and laugh at his jokes even if they are not that funny.
Don’t come off too strong or he might get scared and run away—yes, like a lost puppy.
Believe me, guys are way more delicate than we think. At least the ones that are sane, and not the manipulative d-bags in disguise.
Anyway, pay attention to the first impression you’re going to leave because even if you fuck something up and start all over again, that first impression won’t ever go away; it will stay remembered.