1. If you rigged the character for animation then select objects, click object->clean up->clean up vertex group weights. This removes vertices that have ## weights from vertex groups. By default it’s set to 0.
2. Object–>cleanup ->unused material slots.
3. Cleaning the file. File->cleanup->purge unused data.(Recursive unused data-blocks in older versions of blender).
4. Ctrl+shift+s or file->save as. Open N-panel by pressing N. On the n-panel check compressed. Then save your file. You can give a new name if you want.
