Here are a few tips that will help you get the most out of Annabella. When attaching the pump to the breast, first attach the bottom part and then the top part. While pumping, press the breast shield evenly onto the breast, so that it doesn't "escape" and create a vacuum from above or below. In other words, be careful not to press too hard on the top or bottom, but apply equal pressure to the breast shield. The breast shield has a "peek-a-boo" window at the top, which allows you to clearly see where the nipple is and whether it is centered well, both to the right and left, and also above and below. Note that the nipple should not lean to the side.