You can use Comet of Legend's flight to grow Starsurge to massive proportions.
Save Voice of Light to use as a defense against melee opponents if you need to - otherwise, use its slow to start a fight at long range.
Comet of Legend allows you to move quickly around the map; use it to put pressure on other lanes.
Try to get inside his orbit, since his stars can't hurt you up close.
His stars disappear while stunned or silenced, giving you an easy opportunity to fight him.
He gains speed while chasing in a straight line, but taking damage makes him lose that momentum.
His Starsurge ability can grow to cover a huge area - don't stay in the same place too long!