To extend your E range E and mid animation Flash, then instantly W Q AA.
For a more reliable ult combo Q then release and instantly W. Quickly E after the slow lands then instantly R and continue to cast R until you run out of charges.
To extend your Q range hold Q then Flash and instantly release Q.
For max damage at a long range Q then release and instantly E W R. Continue to cast R until you run out of charges.
Your standard stun combo is E then W Q as soon as you confirm the stun will land.
When looking to poke W then instantly Q, but release it after the slow has landed.
For perfect burst timing W E Q as quickly as you can.