Start off going for Trinity Force for the bonus damage and movement speed on hit, which you'll easily get plenty of by charging your opponent. You shouldn't need any other movement items after that once paired with your legendaries.

Stack Collector, Dominik's, and Kraken slayer for that juicy crit fun, execute ability, and bonus damage vs champs with more hit points. Kraken paired with your basic attack reset from Q and E (when you time it right) will let you dish out a lot of damage quickly.

End with Mortal Reminder or Death's Dance depending on if you need to stop some healing and want more crit chance, or if want more survivability.

Use your E for poke against enemy champs. Definitely try to exploit knowledge gap of mid lane champs (especially ranged) not used to Vi's Relentless Force range and cooldown speed.