|This is so simple I hope I don't offend anyone by posting it.
If you're having trouble sewing close enough to the zipper pull, move it down a few inches so it's out of your way. Sew until you get near the zipper pull, stopping with your needle in the fabric. Lift your presser foot then slide the zipper pull back up to the top. It helps to stop before you get too close to the pull. Now lower your presser foot and finish sewing and it won't be in the way! This is kind of a no-brainer, and won't work in all situations (sometimes it's just too hard to maneuver the pull), but I tend to overlook the simple solutions sometimes.