Just finished this Space Marine Librarian, so I thought I would share it here. It took me a little while to come up with a colour scheme I was happy with (that amount of detail can really confuse things) but I'm pretty happy with how it came out. I wanted to keep the colour of the armour quite deep as I knew there was going to be quite a lot of lighter coloured detail - like the scrolls, parchment and face. I always try and keep the area around the head as deep as possible - then it throws more emphasis on the face.
I used the open hand (there are three variations of the left hand in the blister) rather than a weapon - and added a 'magical' effect in the palm, as if he is gathering power for a psychic attack.
I kept the colour scheme for the base to a fairly limited palette - there is so much detail and texture on the miniature itself, I didn't want the base fighting against it. I also chose a colour scheme that would contrast with the Librarian.