this are good lessons: http://curriculum.autodesk.com/student/public/teacherresource/curriculum/id/40/page/1# just launch the curriculum "Maya vehicle for games"and you will learn a lot of usseful stuff
1. Use hard edges at very harsh angles. Abuse this if synched. 2. After you unwrapped, set your hard edges to your uv island boundries, there are scripts that do this automatically. 3. Force triangulate before exporting out of your 3D package 4. Do test bakes. I recommend creating a high poly cube and test your hard…
I took a look at your low poly and there are some major issues. Did you export the FBX with smoothing groups? Because the file I loaded had none. On top of that you have a ton of edges that converge to a single vertex. For baking purposes this can cause major issues when baking. Without smoothing groups I can't really help…