Especially when you too argue try to listen first before speaking and assuming what he wants to say. Make him believe that even though you don't agree to him but you make it a point to LISTEN.
4. Become his best buddy.
Okay you are his girlfriend. Agreed. But, every once in a while try switching your all-time-serious-girlfriend role to his buddy forever. Men long for a best friend more than anything else.
5. Don't hold back things.
Don't wait for the right moment to remind him about the mistake he did three days back, that mind game is EVIL! If something is bothering you be vocal about it.
Communication is the key to a happy relationship.