When laning, use Void Rift to kill minions while building stacks of Organic Deconstruction on your opponent. You can then follow up with your other abilities.
Shooting Plasma Fission diagonally and splitting at maximum range allows you to hit opponents that are out of the range of the initial missile, but is more challenging to pull off.
Be very careful about when to use Life Form Disintegration Ray. Many champions have abilities that can interrupt the spell.
Vel'Koz is very dangerous if left alone in a fight. Try to focus him down early.
Vel'Koz has fairly low mobility and is vulnerable to ganks.
Life Form Disintegration Ray can be interrupted by stuns, silences and knockups.