To have a better effect, try using different colors or tones from the one(s) you have on your model. After all, the stowage in the form of jerrycans, boxes, tools, battlefield 'souvenirs', tarps,.. were manufactured by different companies than your tank (well, in all likelihood anyway). Use slightly different tones for each tarp, crate, jerrycan or drums too. Use washes and drybrushing accordingly, but weather them the same way as your model (same colors, same pastels,..).