Common mistakes when texturing normal maps for 3D models include incorrect tangent space alignment, over-exaggerated details, and poor UV unwrapping.
Incorrect tangent space means the normal map doesn’t match the software’s surface direction calculation, leading to glitchy lighting or misaligned shadows. Over-exaggerating small details (like scratches) creates an artificial, "plastic" look instead of subtle variation. Poor UVs—stretched or overlapping—distort the normal map, ruining realism.
For troubleshooting, use real-time previews to check light interaction and keep details proportional to the model’s scale to avoid overdoing it.