A bit different in each matchup - find what works for you
Walloffs are incredibly important
Hellbats once you have armoury
Gas takes Priority
Engi Bay + Turret timing might need to be adjusted some games to before you add your 3rd-5th factories. However if you just get surprised 1/10 games or less then don’t bother too much. Mech always has some small vulnerabilities and you don’t want to start playing overly safe. So just follow the build at first and if you llose the odd game to air/drops don’t stress over it.