Hi bultenido,
For the ultimate reference on german uniforms you need the following 2 books:
German Soldiers of WWII by Jean De Lagarde. Published by Histoire. ISBN 9782915239355.
This book contains over 130 pages of full colour genuine german uniforms worm by models from all services. Also includes insignia detail and equiptment again all authentis WWII items.
The second book is:
Feldbluse "The German Soldiers Field Tunic 1933-1945" by Laurent Huart & Jean-Philippe Borg. Published by Histoire. ISBN 9782352501000.
Again this book details genuine items but is devoted to the Tunic. It is full of colour photos and details colour, style, material and construction changes for the pre war years through the combat years.
You will be able to see the actual colour and mix your own for scale effect.
I can try to take some pictures and post them if you need convincing!