Check the VirtualBox guide for errors, spelling mistakes and if it is up to date.  Follow all links to make sure they're not stale. Step-by-step verify the instructions. Add any steps or info that is missing.

Are there any TODOs that still need to be added? Are the screenshots of good quality or do they need to replaced?  Have any steps been missed or not explained right?

It looks like the last screenshot has not been cropped right.