Building Debian packages

[Andrew Wood <a.j.w@me.com>]

Im trying to learn how to build debs.

Ive been reading the Debian GNU/Linux Bible published by Wiley in 2005 
which gives a good run through of building debs using dh_make and its 
relted tools but Im a little confused about the best way to layout the 
directory structure.

dh_make insists on having the upstream source in a directory called 
project-version For the example Im using which is the Firefox 4 source 
Ive called this firefox-4.0.1

Assuming this directory is in my home directory I've got ~/firefox-4.0.1

Running dh_make creates a subdirectory ~/firefox-4.0.1/debian which 
contains all the necessary files for making the deb. including the 
changelog file

My question is, if i replace the source tree with an updated version, 
say 4.0.2 when its released, I will loose the debian directory, and 
withit, the changelog file.

To my mind, the debian directory ought to be in the parent, so I might have
~/firefox/debian &
~/firefox/firefox-4.0.1

That way any stuff to do with packaging, especially the changelog, will 
be preserved even if I swap the source for a different upstream version.

Can anyone advise me please?

Andrew