Your passive works well if you are able to switch in between hitting multiple targets without having to burst down one champion. You can usually do this during ganks, when you are sure both opponents are going to die so you just hit them both switching between targets to apply the passive as much as possible.
You want to equip Q since level 1, but W is also an option to push the wave sligthly faster. Look to Q low HP minions, especially ranged ones, when an opponent is standing behind the low hp minion, or when going for last hit. Keep in mind the Q crits if it kills the first target so it can deal a BUNCH of damage. If you kill an target with Q it crits when jumping to another one, which can deal a TON of damage during lane phase, because it also works with minions. If your opponent is standing behind an low hp minion, feel free to last-hit the minion with the Q and use your AA cd on the champ instead of the cs, this way, you can deal a ton of dmg in a very short time. Also keep in mind that your Q applies on hit effect, therefore it can help you with resetting your passive. Auto-Attack on opponent A while you using Q on opponent B, then your next AA right away on the same opponent, A will proc the passive again because Q procced it on the B.
In fights, if you have strong enough frontline, you can look to position yourself purely to use a good ultimate. If you land it at 2 or more targets, it will deal more damage than you would usually do with auto-attacks.
Your W passive makes you run faster if you do not get hit in a while, you can also use the W to get the speed and bonus attack speed immediately, reducing the cooldown when shooting unique/switching between targets (applying your passive).
If you are stomping lane phase, especially against an early game team, and recall at 450/900/1350 golds, you can spam doran blades into your inventory to increase your lane power ever more
. These Doran blades are not just useful during the lane phase but help you in the later phases of the game as well, however, makes completing items a little more difficult as you can't really stack components in your inventory anymore coz out of slots.