I've read my copy of gettinther's old school Setting Up a Build Environment...
You probably already know this, but it looks like old posts on it have been put to rest, so I'll post it anyway..
EDIT: Martin beat me to it!
..installing pkgutils from the repo will set up your RPM build environment, including setting up a local repo and adding it to your sources.list. The DE / file-manager specific packages will also create convenient right-click context menu options for many common operations, including "installing" any downloaded SRPM to your packaging directories for easy updates / modification.
The local repo's package lists will have to be updated after any new package that is built if you want it to show up in synaptic for install. This is done using pkgutils gbd
script in console as the packaging user (..with one of the DE specific pkgutils packages installed you can also install any RPM using apt-get via a simple right-click context menu in the file manager
There is a description of all of the "helper scripts" that are included in pkgutils in the package description in synaptic.