How to not install recommended and suggested packages?
If you do not want to install recomended packages you can run apt-get with the --no-install-recommends flag or aptitude with the --without-recommends/-R flag.
If you want these flags to always be enabled (I do NOT recommend this) put the following lines in your /etc/apt/apt.conf file:
APT::Get::Install-Recommends "false";
APT::Get::Install-Suggests "false";
Remember that these packages are recommended for a reason and it is probably not a good idea to ignore it at all times. You would be better off using the flags in the cases where you know that the recommended packages are wrong.
According to me, changing conf files are too risky and unnecessary. Rather apt-get provides options to specify do not install recommended packages.
sudo apt-get install --no-install-recommends package-name
This is better than changing conf file.
The correct syntax in recent versions appears to be:
APT::Install-Suggests "0";
APT::Install-Recommends "0";
You can put this in /etc/apt/apt.conf (which no longer exists by default) or in a file such as 99local in /etc/apt/apt.conf.d.
Watch out for any other files in /etc/apt/apt.conf.d which may override your settings.