This blog has some great advice for guys meeting the parents for the first time titled Leave them at the door.
When it comes to meeting anyone knew leave all your bad habits at the door when you walk in and meet new people. Do not be one the suggests drinking smoking or doing anything bad and of course do not come in smelling like smoke or dressed bad. Always looking sharp and smelling sweet is part of the cool guy code so make sure to do it already.
Great advice it should not be taken lightly! Take it from a mother and parent.