This Day of Defeat mapping tutorial is presented in a video format and can be downloaded here. Though it is focused on building a map for the original DoD, the fundamentals and many of the points discussed can be applied to DoD: Source, HL and Counter-Strike.
Please note that I did not create this tutorial and nor do I know the editor other than the fact that he calls himself "RJ". This is a great tutorial which was long-ago lost so I have decided to resurrect it, hoping that it may help other people as much as it has helped me. I have included a few screenshots below for preview purposes.