To prepare a change to a regular package (a source tree containing a debian/ subdir), make the edits in a checkout and record a changelog entry. You can either edit debian/changelog using emacs changelog mode (C-c C-v to add a new version entry, C-c C-a to add a change entry, C-c C-f to finalize the entry) or you can run "dadch" from the debathena locker / SVN scripts directory.

When creating a new version entry, bump the upstream version number (to 10.0.0 if it was not already that high) if you are changing the main package source. Otherwise, just bump the Debian version component (change 0debathena1 to 0debathena2, for instance).