The key to this is poking with auto attacks and your Q while still managing your mana to have enough left to E away from any possible gank or damage you can't afford to trade for.
I personally don't like the new Trinity force with the hits it too in the S3 update therefore i haven't prioritized it in the guide at all, however if you are a fan you can swap out a Phantom Dancer in the guide and replace it with a Trinity Force.
Depending on who you are laning with, will depend on how aggressive you are and how you play this aggression. If you're with Soraka, Use your Q everytime it's off cooldown to poke their weakest champion, taking into account if they have a heal and whether its targeted and its cooldown. If with a Taric, save your mana and burst Q,W auto attack everytime he stuns. You can use E for poke if your SURE you're not going to need it to evade a gank. if with an Alistair or Leona when they lay cc down, lead with Q and auto attacks hitting your support with W and sustain your damage over time while retreating once the CC is worn off. If laning with a Zyra play as you would with Taric, burst and high single target output. If playing with a Blitzcrank, decide whether the pulled champion is killeable, if so E into position and get Q, W and then continue Q follow up after auto attacks if needed.
Later in game make sure you position yourself around the edges of the teamfights using your high maneuverability to secure kills and to dive in and out of teamfights when necessary, Using your ultimate when you can hit the most consecutive targets in a row, preferring the Squishiest as your first hit if possible. Use your W to ensure you can raise your Passive stacks up as quickly as possible, and periodically reset the cooldown on it by using your spells effectively to re-trigger the passive stacks.