To engage from further away than expected R and instantly Flash Q W, then AA E followed by AA E AA.
To quickly use your spell rotation and mop up a kill W and instantly E. While in mid air cast R so that it finishes its cast as you arrive, then quickly Q AA.
To E three times in one teamfight Q E your first target instantly but make sure your Q hits your second target. AA upon landing, E to your second target and R AA. E your third target instantly before your R damage lands, then AA upon arriving.
For surprise burst damage on the enemy backline in a teamfight W AA your first target then R AA and instantly E your main target. Cast Q as quickly as you can then AA.
For a long range all in to get onto the carries in a teamfight Q E your first target then R and instantly Flash to your next. Use W once they are pulled together and AA twice then E AA.
To quickly burst a low HP target W, instantly Flash and E Q as quickly as you can.
To burst your target E then R mid air. Use W Q while they are knocked up then AA three times to proc Diana's passive.
Your basic level 6 all in is to Q E instantly and use W mid air. Upon landing AA R AA then E and AA as the follow up.
For a melee range all in W then AA twice, use Q E instantly and AA three times. E again, then AA once more.
You can sneakily trade with your passive. AA your first target twice then Q E your main target. Instantly AA W upon landing, then E back to safety on a different enemy.
To trade while hiding your first attack AA and W as soon as the animation starts. Instantly Q followed by more AAs.