Its often considered better practice to use the sudo command rather than switch to the root user
The sudo command allows you to perform actions as root but logs the actions you take (so you can trace anything that was done to the system by yourself or others). sudo has a
very good manual page which provides plenty of information about it.
You use sudo similar to how you execute a normal command with sudo prepended to it, for example:
sudo rpm -U myrpm.i386.rpm
This would allow you to install a rpm even if you have the correct sudo access