I am making my own LotR-themed Risk game and I am having trouble finding a very accurate map of Arda before Beleriand was lost. This map should include Valinor and Númenor as well.
The best I can find so far appears to be a map from David Day's "Tolkien Bestiary"
David Day's map is widely regarded as one of the worst examples of Arda. His work is often criticised in the Tolkien community. Your best bet is to stitch together a number of maps.
One map superimposes a sunken Beleriand on to Western Middle-earth seen here
The rest of Middle-earth can be seen here:
A map of Beleriand which was drawn by Tolkien:
As far as I remember there are no good maps of Arda that include Aman. I can't of the top of my head even remember if there was a map of Aman drawn. Outside of Tolkien's own drawings The Atlas of Middle-earth is probably your best shot.
As @Joel pointed out resources on Aman can be found in The Atlas of Middle-earth, it's not canon but apparently very good.
You can't get more accurate than a map drawn by Tolkien himself. Here is one such map:
And a much larger, more legible version of the same map, drawn from Tolkien's original, by Karen Wynn Fontstadt:
Because Númenor and Beleriand didn't exist at the same time, it is impossible to find an accurate map showing both. Here is Karen Wynn Fontstadt's map of Arda in the Second Age, including Númenor (but not Beleriand):
Note: Click the links to see the full size maps
