source package using "apt-get source packagename" where "packagename"
is the name of your source package or any of the binary
packages it produces. This will download the orig.tar.gz,
diff.gz and dsc source files for your package, and unpack
and patch the source code in a new source directory.
the Build-Depends list in the dsc file, and make sure you
have all of those packages installed. Also, make sure you
do not have any of the packages in the Build-Conflicts list,
if there is one.
the source directory and type (as root) "debian/rules
binary" (or as non-root) "fakeroot debian/rules binary".
This will automatically go through all of the steps
necessary to build your package.
Optimization for Debian
You can often increase the performance of an
application considerably by building it with optimization, which
is done by setting compiler flags. An aggressive optimization
setting is "-O6 -mcpu=whatever" where "whatever" is your target
processor, but beware such aggressive optimization can lead to
errors! See the gcc man page for details. The debian/rules
file is usually where you want to set the optimization flags,
typically using the CFLAGS variable in the configure line, e.g.
"CFLAGS='-O6 -mcpu=ev56' ./configure <configure flags>", this is
done between steps 3 and 5 above.