The RedHat installer will prompt you to install a certain number of
packages. My suggestion is to exclude
only those packages you know you'll never use. If in doubt, include
them, you'll be able to remove them later. Do not forget that many
libraries with exotic names could be sooner or later necessary for
compiling programs; so think twice before removing them.
To remove a package you just have to type rpm -e package_name, the complete list of packages will be displayed typing rpm -qa. Refer to the RedHat manual for the complete explanation of the rpm command.
The RedHat manual says that a 80Mb root partition should be enough. I've noticed that some packages (e.g., KDE, Netscape are installed in the /opt/ directory, filling up the root partition. In order to avoid that you can either create a larger root or type the following commands:
rm -rf opt
ln -s /usr/opt/
this will create a symbolic link to the directory /usr/opt/ in the / partition. Please note that, in this way, the /opt directory is completely erased. Of course all that does not apply if you decided not to use different partitions for / and /usr.