And you wish to be civilized.
Your journey starts now.
Step 1: Open the Bag.
NOW you would like to consume the tasty snacks, so thusly you must open the bag and free the deliciousness from its mylar prison.
The commonly chosen methodology is to pinch the seam on the back of the bag, and the frontspiece similarly and gently but firmly pull the plastic apart. This will open the bag easily and prepare you for step 2.
Step 2: Identification and Controlled Opening.
Locate the corner of the bag that you had pulled apart. the corner piece will be weak, and easy to tear. (it like if you want to rip a T-shirt off of a chippendale -- you generally need a starter cut to tear the shirt without mussing your hair or breaking an un-sexy sweat.)
At that corner, use both hands to pinch the mylar -- one pinch on each side of the corner. And in a "tearing motion" use the weak point to start the opening - taking it in the direction of the front of the bag.
Grace is paramount!
Step 3: Tear in an Arch...
While tearing -- which will be more of a "glide" as mylar splits easily -- you will giude the tear into an arch that will go about 1/2 way down the bag, and then up to the other weak corner.
This motion should be smooth, for additional levels of classiness.
Step 4: The Completion of the Tear.
I highly suggest wiping off the mylar, removing the seam with a scissors (or another deft tear) and wrapping it tightly around a pencil or marker from the office shiny side out, creating a 2.5-3" extension to the pen, and securing it with a piece of scotch tape, and then making several narrow vertical slits in the tube, and crumbling up the fringes to make your very own pon-pom/faux silver spider plant/magic wand writing implement. But that is just a suggestion.
Step 5: Serve and Eat the Snacks.
(a shallower arch will allow for leftovers and folding and clipping for storage, if you were to procure a *large* bag of snacks, and you were inclined to take the remaining chips home to your current paramour.