Hi Ragnar2004,
First let me say, welcome.
On the ambush scheme, I think about all the German schemes were pretty much left up to the individual crews.
That being the case, I would paint your base coat of yellow and follow with large patches of red-brown and or green. Then it is simply a matter of adding the small patches of color.
You could put patches of the red-brown and green on the yellow and patches of yellow on the large patches of red-brown and green.
Put small patches of red-brown on the large areas of yellow and green.
I think you get the idea. I just don't think there are any hard and fast rules when it comes to German camo.
Just use your imagination.
Sorry, I couldn't give you a specific article to refer to. Look in some of the galleries on the different sites and you can see some great camo jobs that should help you in making your decision.
Regards,
Joe