Installing Drupal6.4 on Debian4 + Apache2

I had to install Drupal today on one of our servers. I ran into a few minor problems:

• There were some problems with file permissions in the drupal/sites folder, so I changed owner and group of some files and folders to www-data.
• Drupal complained that the PHP GD library is not installed: just run apt-get install php5-gd and restart Apache.
• Drupal couldn't send mails, so I installed postfix (sudo apt-get install postfix), set the server for outgoing mail (here called the "smart server") to our institute's smtp server, and used mailx to test it.