After a few more hours of work and experimentation I have made more progress.
The actual Slann is pretty much finished at this point. Only the palanquin remains. To finish him off, I dry brushed the main body with Fortress Grey to give him a slightly more aged look and then applied a second coat of Devlan Mud. This made the grey highlights really pop and I think created a really cool effect. I then coated the jewelry pieces with Dwarf Bronze, applied Skull White to the teeth, and gave him Space Wolves Grey eyes. After touching up the areas around these, I washed the teeth and jewelry with some Devlan Mud.
I didn't add a pupil to the eyes because I was thinking it would be cool to give him eyes that were reflective of the sky and then leave them looking like he was in a trance with his eyes rolled back or possibly blind or meditating on matters of great importance.
The palanquin has not made much progress in comparison as I have been trying to decide between a few different colors for some of the pieces. In these pictures you can see some of my experimentation.
I'm trying to make a decision between Snot Green and Dark Angels Green for the leaves. I'm not sure which seems more jungly. I'm not sure either actually looks quite the way I'd like it to. Any suggestions?
I'm also experiencing the same dilemma deciding on the color of the branches. On the picture you can see where I've tested out Scorched Brown, Bestial Brown, Vermin Brown, and Calthan Brown. Neither is quite what I want I don't think.
I've started to coat the decorative pieces in Dwarf Bronze (eventually going to coat with Devlan Mud) to match the Slann. I'm not sure I want the round parts where the tusks/horns are mounted to be this color though. I need to think on it some more.
The last issue I'm grappling with is the tusks/horns themselves. I had initially coated them with Skull White with the idea that I would dirty them up a little bit but I'm not sure I like the effect the Devlan Mud has had. It's almost too dirty. I need to find a good way to give these shading and make the white slightly less pristine without just making them look brownish.