Glitterlance can be fired at odd angles depending on where your cursor is - Moving your cursor closer to Pix and Lulu will change your area of effect size considerably.
Consider casting Help, Pix! on ranged attackers for the Pix boost and Wild Growth on Tanks or Fighters for the added initiation power.
The shots from Lulu's faerie can be intercepted - hide behind your minions to avoid the additional Faerie attacks.
Lulu excels when opponents heavily commit. Don't give her this chance! Use heavy harass tactics instead to force Lulu and her partner out of lane.