/u/Rob-With-One-B has an answer here which I think does a good job of explaining the tactics used in the War and why the Prussians' were superior to the French.

If I could add one thing to that answer, it would be why the uniforms didn't make much of a difference. As mentioned in Rob's answer, at the most basic level, the tactics employed maintained a similarity with those used in the Napoleonic Wars over half a century before, with lines of infantry marching towards one another and firing in volleys. When infantry are deployed in this manner, camouflage becomes irrelevant. Instead, colourful uniforms become useful as a means to identify allies and follow orders in battle.

Why was this? In the Napeolonic Wars, the inaccuracy of musket fire meant massed fire was the most effective way to hit your foe. But advances in techonology made guns far more accurate. So why the old tactics?

The answer is an accurate gun is no good if you can't see. Smokeless powder would not be invented until after the War meaning that after a few volleys of fire, visibility on the battlefield would be greatly reduced. This would prevent accurate aiming, maintaining the utitilty of deploying infantry in lines and coloumns.