Measure the zipper opening in your project and mark these measurements on the zipper.
Cut a fabric rectangle of 3" x 2 1/2". So the width is 2 times the zipper width plus 1/4" allowance on each side of the rectangle; if it sounds confusing, it will make more sense in the next steps). The length depends on the method you choose for inserting the zipper into your project. In my case, my final zipper tab was 1 1/2" long by 1" wide.
Fold the rectangle in half, lengthwise and mark the crease.
With the fabric wrong side up, fold each half towards the crease and press with the iron on steam.
Turn the strip to the other side and fold in half, widthwise.
Sew the raw edges together with 1/4" allowance.
Finger press the seam open (if the fabric is too stiff, press with your iron too).
Turn the little tube right side out, with the seam in the middle, and press well.
With the tab seam down, insert the zipper into the tab and align the bottom end of the tab with the mark on the zipper. The zipper teeth should be on the right side of the zipper tab (the seam in the zipper tab should be on the wrong side of the zipper). Then pull the tab to slightly cover the mark. If the tab will be sewn within the seam of your project, pull the tab a little more. If the tab will be completely outside the seam allowance, then you need to pull it even more.
Next step is to edge stitch the top of the tab.
Then pull the tab up and trim the zipper on the mark.
Push the zipper tab back and edge stitch the bottom.
Repeat for the other tab on the opposite end of the zipper (the zipper pull end). For this end you'll first need to pull the zipper pull out of the way and secure the ends of the zipper by running a line of stitches just above the zipper end. It helps to temporary sew the zipper teeth by hand, just below the zipper pull.
And that's it, you're zipper tabs are done and your zipper is ready to be inserted into your project!