Here are the things you can do according to qole:
=>apt-get install localepurge; localepurge (frees up some space)

and mount /debian/var/cache/apt/archives to internal/external media coz while installing/upgrading packages are downloaded which are much larger than the files being installed or upgraded so this will download the packages to different location other than device memory:
=>mkdir -p /media/mmc1/apt-archives/partial
=>sudo mount -o bind /media/mmc1/apt-archives /debian/var/cache/apt/archives

You can use mmc2 if you prefer and shoud give this command in non-debian prompt.

*Also what I did was removed files from the following directory:
/usr/share/doc (gave me back 50+ MB)

=>sudo aptitude purge $(dpkg -l | grep '^rc' | awk '{print $2}') to completely remove the configuration files after the package has been removed

and you can do 'sudo apt-get autoremove' to remove packages that were installed while installing other packages and are no longer required

Hope these helps...