A method that hasn't failed me yet, touch wood, is:
Conscript -> Maxim -> Maxim/Mortar -> ATgun -> Shocks -> ISU-152
Building the conscript, at the same time as tier 2, let's me seize areas of the map quicker.
The first maxim is a must as it can help your Conscript take out the far superior Volks or Sturmpios( A little suppression goes a long way

)
The second maxim is to be used if the map is very open or you need to lock down more than one route at once. The mortar is for if one mg is working fine and you want something to force them out of cover, so that they get suppressed before the Conscripts are sent in, or to counter mg34s.
The AT gun provides decent defence against their flak half track upgrades and also allows you to force them to attack if you can get their panzer truck or medic truck in range.
Once the shocks hit the field their infantry is easily beaten. You can vet up your shocks quickly against their standard units and, once vet 1, shouldn't have an issue against their fallschirmjager.
With some aggressive play from the shocks and at guns, you should be able to cut off their fuel and buy enough time to wait for the ISU, which works great against any blobs they develop to counter your shocks aswell as providing the long range at that your army is lacking by this point. ALWAYS keep a shock unit close to the ISU. This is to mop up any panzershrek units they send around the side. It can also help to keep within range of your field ATgun too, if they send some pumas your way.
If you feel that they have collected too much fuel for your liking, don't hesitate to spend muni on mining the flanks. Just make sure that you keep enough for smoke and nades for your shock troops.
I've yet to play against a vehicle heavy OKW player so I don't know how this will fare against them, but it's working well so far. The tactic also translated well into 2v2 and 3v3 aswell.