I'll just lay this out in steps.
1. Do not ruch for your MC this takes away from what could be stalker and zealots far more useful. Besides the game is already decide long before you will ever have photon overcharge when you are being proxy 2 gated.
2. cut probes immediatly.
3.Building placement is crucial you want your first pylons and gateways to be hugging your nexus making little pathways to kite zealots around in.
4. Chrono out a zealot, if you can chrono out a stalker and keep chronoing them out and get a second gate when you can.
5. Use your probes to delay his initial zealots not fight them. you want to pull some probes but leave some mining as well. Once your first unit pops use your probes to help it then pull them back only fully commit your probes if you think you have won.
6. Micro the whole goal is to get 1 fighting unit a head and you should win.
7. Scouting: these are pretty easy to scout, what you do is just go straight to the source your oppenents base they can't hide the fact that they are missing just about everything that should be there. Alot times you will have to pylon scout to get the info in time some maps you can gateway scout and still get it in time. Other methods is to scout around your base and natural immediatly after starting your first gate. However, some people like to put their gates outside your third area and thus make it hard to scout if your being 2 gated that way. Which if unscouted and they charge in with 3 zealots it can get rally dicy to hold depending on what build you opened.
8. Almost forgot cannons are not the answer and against a good player you will lose. By the time the forge and then cannon get up again the game will already be decided on who is going to win most likely the proxier since you wasted 300 minerals that could have went to fighting units and a second gate.