To hide your Shark, Q then mid dash R followed by a quick double tap of E to get into range for AA W damage.
Use E towards your opponent. When you start to fall down Flash on your target before you hit the ground, then AA W and instantly Q.
Guarantee your ultimate by Q then mid dash R and mid animation Flash onto your target.
To trade and retreat without damage E behind your target then activate W before Q back through them.
Another way to poke is to double tap E to engage then AA W instantly. Get behind your opponent to be able to Q back to safety.
Quickly burst with R and hit E to engage. Once you land, AA W Q as quickly as possible.
From close range R and walk up to AA W, time E with the knockup then AA Q.
All In after level 6 by using R then walk into Q range, instantly AA W and then quickly double tap E.
To All In from range E onto your target, then when you land AA W. Continue to AA and use Q to stay in range.
To All In early Q then AA W instantly and use E right after for damage.
The most common poke trade is to Q then AA W instantly and use E twice to quickly get out.