Remove the Basting and Un-Zip
Since my zipper is too long for the front of the garment, I trim it and add some safety pins to anchor the edges. This prevents the zipper-pulls from flying off and landing under the couch (don't ask...).
Having the fronts seperated will make the actual sewing easier to handle and allow you to perfectly align the edge of the teeth slightly in from the edge of the front.
You should NOT be able to see the teeth edges from the Right-Side of your garment when the zipper is zipped...
NOTE: if you are going to hand sew your zipper, continue from this point. I like to use a Back Stitch to firmly sew the zipper to the sweater fronts and I use ButtonHole Twist Thread in a matching color.