-First make 8 probes then build a pylon near ur Nexus. (Build a ninth probe while that pylon is building)
-Build another pylon by the entrance or antrances to your base.
-Build 3 Forges by the one closer to your Nexus upgrade all three things continuously.
-If there is one entrance build 15 photon cannons by it, but if there's more than 1 build 7 by each.
-Build a line of 7 pylons going downward.
-Then build 10 Gateways, 5 on each side.
-Make the gateways teams by clicking one then hitting Ctrl and 1 then click the next Ctrl and 2 and so on.
-Make 1 Cybernetics Core.
-Upgrade Dragoon attack range.
-After that build a Citidel of Adun and 3 Stargates.
-When the Citidel of Adun is done build a Templar Archives then a Arbiter Tribunal.
-Upgrade Recall and +50 energy.
-While all this is happening, keep your defense steady and dragoons coming all the time. (Since you've made the Gateways teams, you can click 1d2d3d4d5d6d7d8d9d0d and it'll make 10 dragoons, 1 in each Gateway.)
-Build 6 Arbiters.
-Find a spot in their base that doesn't have any defense and send in your Arbiters. -Recall in your dragoons and watch them die(It might not work the first time, but keep at it and you'll get better.)

CreepColony's Opinion: I don't think six arbiter are necessary, just 1 or 2, with hallucinations to distract their air defense.