craftgrrl | Question for my seamstress/tailor-type peeps

Even though I've been sewing for a while now, zippers continue to be my mortal enemy. More cursing and seamripping has happened in my studio than I care to say. I actually just sewed a zipper in quite well on the first try, but continue to experience one of my major problems. And so I pose this question:

When you install a zipper, how do you keep the zipper foot from riding up on the zipper pull and creating an unsightly "bump" or curve in your stitching?

If someone can help me with this, I swear it will be like a light shining down from the heavens.

And I can't believe I haven't thought to ask you all before - Lord knows I've been in this group long enough!