Note: Get help from an instructor if you need help importing it!
Blender's supported files: FBX, STL, DAE, 3DS, OBJ
Places to get free models:
* https://www.deviantart.com/ (Search "3D Model")
Or Google "3D free character models"
First if your 3D model is rigged, select the bones and press H to hide it, then select your model's mesh and add the Decimate modifier.
Shortcut keys learned: [H] - To hide the currently selected object [H + ALT] - To unhide all objects
When a model has too many Verts, Tris, and Faces. Let's say around 2 million. Your Blender will become very laggy, and if you have anymore than that, Blender.exe will crash.
And if you use a 2 million polygon(verts,tris,faces) 3D model in Unity, it will take forever to load or it will also Crash Unity.exe!!!!
So with the Decimate Modifier, you can adjust your 3D model down enough to a point where it still looks okay and the polygon count is cut in half or even down to like 30% of what it was!
WARNING: This step is optional! It's only for testing what will happen if we have too many polygons! Beware if you had any unsaved work and make sure to save it!
Press Subdivide again and repeat this process until you can feel the lag.
Then add the decimate modifier and see if you can get the poly count back down to around 10~30k! (depending on your model)