Runaan's is optional, but highly recommended as it applies your blighted quiver (w) to three targets at once, as well as the BotRK on-hit. If you want more AoE, replace PD with static shiv.

This is a generic mastery page, I prefer 21-0-9, or 19-0-11, but this is easier for less experienced players.

I personally use 2 LS quints while running 19-0-11 masteries to have 7% lifesteal, while still gaining a good amount of AD from both runes and masteries. I would only recommend that if you are very good at trading.

Maxing Q instead of E gives insane poke in lane, especially if blighted quiver stacks are applied.

Against a healing support, you can max E isntead of Q to apply grevious wounds, but It does not junk as much as maxing Q.

Varus's passive gives bonus attack speed for last hitting minions and champions. This includes jungle mobs. I recommend utilizing it by harassing after last hits while you have bonus attack speed, as you will be able to harass more than the opposing ADC.