Step 2: Cutting your bags into strips.
It is very important to cut these strips pretty wide. For most normal sized bags, it is possible to get three continuous strips about 4 inches wide. I never got out a ruler, but it's very useful to size up the side seam of the bag before you start cutting to determine how many strips you'll be able to cut.
Lay out a plastic bag, and fold in the sides as shown in picture two. Snip off the very top/handles and the very bottom. Then open the bag to its full width.
Turn the bag so a side seam is facing you, and cut up and to the right in a sweeping motion until you get at least four inches in, and then begin cutting in a straight line. When you get near the side seam, slip a hand in the bag and turn it so that the side seam is flat and you can start on the second strip.
Cut up and to the right again, mirroring the first time you did it, and then cut straight until you reach a point where you have one closed strip left. You're going to make another diagonal cut to the right, this time cutting to the very edge of the bag.
So essentially, just keep cutting towards the right and mirroring the original diagonal cut. The pictures will give you a better idea of how to do this. :)
You will need to do this to three bags to start your braid, though I suggest doing this whole process as you were a one person factory line - flatten all the bags you have, cut off the tops and bottoms, and then cut them all into strips, hanging the strips somewhere they won't get too tangled. Then begin your braiding.