Usually I sew the zippers with the zipper on the left side. My husband is a leftie, so alle zippers are on the right (when the zipper is closed).

The original tutorial for the zippers is actually a good one!

There are two steps to sew the zippers to the pockets:
- sew the zipper to the fabric
- sew the next piece of fabric to the other half of the zipper.

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UPDATE:
crazymomquilts.blogspot.de/2014/10/sew-together-bag-with-modifications.html
You find a very good modification here, I will try that when I make the next bag!
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1. Step, zipper to fabric

- Fold the zipper in half and put a pin in the middle
- Fold piece B and put a pin in the middle on the top
- Fold piece G and put a pin in the middle

- lay piece B on the table, right side up
- zipper on top, right side down
- piece G on top, right side down

Make sure that the pins are on top of each other, pin everything together with Wonderclips, take the pins out:

The edges of the fabrics don’t meet, the zipper is longer anyway. But that doesn’t matter, you will cut everything later.

Now put your zipper-foot on the machine and sew everything together with ¼ inch seamallowance. The stitchlength should be 2,0.

Now you are back at the iron-board: Press the seam, then fold piece G (inner part of the pocket) open and iron the seam, then fold zipper with piece G again so you can see only the right side of piece B. Iron again.

Back to the sewing-machine! Much more fun than ironing, at least for me. Topstitch that seam, stitchlength 3,0
On the photos you see the topstitching on the right side of piece not very good (black on black), much easier to see on the back (i.e. piece G).

From now on always: - sew the zipper with stitchlength 2,0 - topstitch the zipper with 3,0

2. Step: sew the next piece of fabric to the other half of the zipper

Sew piece C and the 2nd piece G to the zipper
Same procedure as before: fold all three parts and put a pin in the middle

On the following photo you can see the lower part of piece C, right side up.
Put the zipper on top (the zipper is already attached to piece B and the 1st G-piece), right side down.
Put the 2nd G-piece on top, right side down.

And again: make sure that the pins match and fix everything with Wonderclips

Stitch everything together (stitchlength 2,0), iron and top-stitch  (stitchlength 3,0).