Trousers and shirts
I mix 2 parts black with 1 part white and 1 part burnt sienna for basecoat, and 1 extra part of burnt sienna for highlights, and an extra part black for shadows. There is a bit of green in the sienna which prevents it going into the brown/ mud/ grey range.
Don't forget that the quality of fabric used to manufacture German uniforms deteriorated throughout the war, so the "grey" will vary depending on what year of the war your figure is set in. Pre and early war uniforms were green-grey and they became progressively greyer as the war progressed.
Often the soldiers shirt will be a very different shade of grey from the pants, depending on the terrain, how long the soldier has been wearing them and his rank. The German Army, like every other army in history ensured its upper ranks wore uniforms made from the best materials
, while the lower ranks got the cheapest and most abundant materials
.
Most infantry soldiers go through 1-2 pairs of trousers for each shirt that needs to be replaced because of all the kneeling, crawling and scrambling on the ground and wading through water and mud etc etc. Therefore, as a general rule of thumb, soldiers trousers tend to be more faded, dirty and distressed than their shirts.
This might come in handy when you decide to paint your German figure, or any modern soldier figure for that matter. Hope this helps.
Cheers