Do a blockout and identify different materials with colored blocks. Then create an atlas texture sheet in respects to the colored blocks. Similar to this http://chrisholden.net/tutor/modular.htm
For the state the model is in, you have much to many vertices, I think. Start with a basic blockout to get the major forms right, before going into detail.
Blah, need to build machines, Im doodling a scifi tank. Not even sure it needs a thread, but here is a quick blockout! It got lots of guns! Progress... might be posted!