This might be obvious but it took me way too long to figure out! When sewing in a zipper, there is this annoying moment when the presser foot hits the zipper pull and your nice stitches previously parallel to and equally spaced from the zipper threads want to go all wonky. Tutorials say to lift the foot and unzip the zipper, but every time I try this the pull is too bulky to go under the foot. What I’ve been doing wrong: you can’t flip the zipper pull towards you to pull it, you have to either push it from the front or pull it from the opposite side. A bent paperclip works quite well to pull it through.
That weird-looking presser foot is an edgestitch foot. You’re not really supposed to, but I’ve started using one for just about everything (you’d normally use a zipper foot for zippers).
Some zipper pouches in progress: