text: Communication is the power word here.  Talk with the girlfriend and she what their likes and dislikes are, then stay away from the dislikes and make a point to bring up items that interest them.  DO NOT sound rehearsed.  Just be yourself!  You'll do just fine!  Be confident.  Remember first impressions.  Dad will be looking for a confident guy, of course Mom too.  Are you grandchildren material?  That's what they will be looking at.  Oh a nice appearance will be nice, but don't over do it.  Again, be yourself!  Good luck!