One trick to keep in mind is that moving Pix can set up some clutch Glitterlances, especially when escaping. If a jugler comes in, use Help, Pix! strictly on the best position, whether that's on your carry to peel a melee type and give a shield, or on an enemy to get Glitterlance on more of the gankers. For that matter, using Help, Pix! on an out-of-position enemy can land an easy Glitterlance on an otherwise out-of-range target, and can be more effective harrassment than just Pix's mediocre damage.
She's slow as all hell, though, and unlike Sona she can't just spam her E to move quicker. Good warding/CV and good awareness are essential, because if you're out of position you're not going to fix that soon.