1. dselect update
then apt-get install localepurge apt-listbugs apt-listchanges
When installing the localepurge select only the locales you want keep on the system (I generally have the en and all en_US) and say yes to eliminating the man pages. Once done that open the file /etc/locale.gen and delete all the lines that you did not keep to prevent them from being regenerated.
2. dpkg -l | grep xserver-*
Delete all but xserver-common and xserver-xfree86.
3. dpkg -l | grep kde-i18n*
Delete all unless you need some language other than English then keep what you need.
4. Go to Kano's
script page and run at least the remove-servers script.
5. dpkg --get-selections > selections.txt then favorite_editor selections.txt
Examine the file and check out what the packages do with apt-cache show package
if you think you are not going to need it then apt-get -s remove package
if it looks like it is going to remove half the system then do not remove the -s from the command for the simulation and keep the package. Slowly get rid of all the excess packages that you will never use and can cause problems when upgrading and make your life simpler. That is a few quickies off the top of my head.
Edit: Left out a couple of things Guarddog
are two firewalls you can get with apt-get install and KDE 3.2.1 that is now in unstable should be installable but you may want to get a little experience with apt first in case you run into problems.