Hi,
I based my colour schemes on these references:
I bought these ones:
http://viceroybooks.com.au/product_info.php?cPath=36_22_85&products_id=2068&osCsid=d7ls3s9s9jjm9muf80s7ler7gL'Uniforme et Les Armes des Soldats de La Guerre 1914-1918 L&F Funcken. Pub: Casterman, 1971. Two volumes, all colour drawings. Very large and now expensive books with sections on infantry in Vol 1 and cavalry/artillery in Vol 2.
Army Uniforms of World War 1 Andrew Mollo & Pierre Turner, Blandford Press, 1977. ISBN 0-7137-0821-2. Coloured plates of wartime photographs and explanatory text.
World War 1 Infantry in Colour Photographs Laurent Mirouze. Pub: Windrow & Greene. ISBN 1-872004-25-3. Colour photos of preserved uniforms worn by models.
Also The World War One Sourcebook. Philip J. Haythornthwaite. Pub: Arma an Armour Press, 1992. ISBN 1-85409-351-7. Covers all belligerents, with section on Belgium and some b/w pics.
And this post on anoyher foum is also very helpful!
http://www.twcenter.net/forums/showthread.php?398692-WW1-RESEARCH-THREAD-**QUOTES-NEEDED**