Send all your probes to minerals, and begin building them. Once the 8th probe starts building, watch your minerals. As soon as you're about to get 100, take a probe that is going back towards the minerals and make it build a pylon. Don't go too far away from your base doing this, and send it immediately back to the minerals. Keep training probes, and as soon as you get enough money to do so, build a gateway with a probe from minerals. Always send them back to harvest once they've created the building. The 2nd pylon should be built right when your 13th probe comes out. Soon afterwards, when you have enough minerals, build a second gateway with one of the probes harvesting. For protoss, it is essential to have at least two gateways early on all land maps. The 3rd pylon should be made when the 20th unit is building. After this, either an assimilator or another gateway should be built. If the assimilator is built, a cybernetics core should be made afterwards. If you plan on making templars and/or upgrading your zealots, make the cybernetics core right after the assimilator has started building. If you plan on making reavers or scouts, you can make the cybernetics core when your probes have just started harvesting gas. This building order can defend against the fastest zergling rush as long as you help your 1st zealot attack the zerglings with some probes.