Start lining the inner corner of eye with blue eyeliner all the way past the mid point of the eye and use liquid eyeliner to define the tail end of the cat eye. Then using a gel liner or eye pencil, colour the ends and bring both colours to meet. Blend with a small liner brush, or if you have a blue eye shadow in a similar shade, use it to blend and set the eyeliner.
Use blue glitter eyeliner on your lower lash line to amp up the glam factor. Take care to only use glitter that’s safe for use around the eye area (that means craft glitter is out of the question), and to avoid rubbing your eye.