I am fairly new to blender and have been trying to learn on my own with help from tutorials and such, so i still don't know a lot of what to do and how to properly do it. I've been modeling this Iron Man helmet for a cosplay project. I need help with these lines that go down the face plate. I have no idea how to do this without ruining the mesh. Suggestions? Please helpenter image description here
The easiest way would be to make each part of the mask a separate object. I would copy your faceplate as many times as many parts I need, and then reduce each copy into needed part. This way the parts would have proper shape, fit together, and have correct topology.