Forge Fast Expand (FFE)
You should always scout after placing the first Pylon if you are going to fast expand vs Zerg. You can safely place the Nexus down first around 12 or 13 supply if the Spawning Pool was placed at 12 supply for the Zerg player. Anything earlier than a 9-pool should be answered with a Forge first. Remember to save up some Chrono Boost for your Photon Cannons if you suspect a Zergling run-by early on. One well timed Chrono Boosted Cannon can take out 5-6 zerglings very quickly.
FFE transitions into a variety of builds which should be kept as secret as possible from the Zerg player. Getting an early Stalker to hunt down scouting Overlords is therefore very important. Popular follow-ups include, but are not limited to: 2 Stargate Corsairs/Scout, Reaver drops, Reaver/Stalkers, Speedlot timings and Speedlot/Archons pushes.
Lategame Protoss armies should almost always have High Templars and maybe even Reavers in them to trade effectively vs Zerg armies. Carriers are also very helpful if the game drags on for long.