Beating Mech

First of all i would like to mention Wilko, who played a lot vs Mech and sayed a lot how to win vs mech.

In General there are some easy things to know
1. Expand a lot! You will fight cost ineffectivly and you will need a lot of production.

2. Immortal / Archons! That's the most important Unit composition. You can add some Charge Zealots but more important are the other two. Try to keep them on the same level of numbers.
3. Fighting positiong try to let HIM attack into you and dont try to engage in a sieged position.
4. Kill Expensions. You can try to kill some Expensions / Production with cheep Units
Most other important things were allready sayed i guess.