Well with my new found drive for both Skaven and Lord of the Rings, I thought I'd share how I do my Uruk's. They're probably the simplest of Middle-Earth's creatures to paint as it is based around only two major colours really.
50/50 mix of Chaos Black and Boltgun Metal applied to all plate armour
50/50 mix of Scorched Brown and Blood Red applied to the skin
Boltgun Metal dry brushed onto the chainmail.
Badab Black wash everything!
Highlight the armour plates with Boltgun Metal and paint the sword
Highlight the flesh with the original skin mix, leaving the darker colour in the recesses.
Codex Grey dry brush onto the hair
Straps/ Banding painted with scorched brown
2:1 Skin mix and codex grey for a fleshy highlight. (TIP: dry brush the face, as the detail is so fine it easily looks blocky if highlighted normally)
2:1 Codex Grey : Skull White mix for the hair
Fine Chainmail highlights on the sword and armour.
50: 50 Codex Grey : Scorched Brown for the leather/ banding.
Base as desired.
A very quick recipe for Uruk-Hai, which makes a very dark yet fitting scheme for the Uruks in my opinion and this is what I'll be using for my War of the Ring force. If you have any questions or comments, then please feel free to post below.