When I face Zerg nowadays, this is what I tend to do:
I open Nexus, Cyber, Stargate into Oracle harass, then produce 2-3 oracles and use them for scouting and map control.
I go for ground upgrades, storm and a mix of zealots, templars with storm, sentries and archons as my main force.
I send Zealot run-by's and Warp Prisms to harass the zerg's 3rd, focusing on bringing down the hatchery.
I force any early engagements on ramps, choke points and if I do attack, I make sure to use zealots to strike in 2-3 different locations at the same time.
My questions and where I seem to struggle:
- How many gates should I have and by what time? (I always seem to have too little Warp Gates)
- When should 1-1, 2-2, 3-3 be completed? When should Storm be completed?
- When do I take my third?
- When should I be maxed out on my army?
Usually, the game ends by this stage. However, if it lasts longer, what tech switch options do I have? What can Zerg do, what are my options to react?