Planning and Preparation
You will require at least the first Ubuntu installation CD to do a desktop installation. To download Ubuntu, you can go to this official web site: http://www.ubuntu.com/getubuntu/download
This document covers on Ubuntu 6.02, but is applicable to most other versions. You will need to configure your system's CMOS to tell it that you wish to boot off the CD-ROM drive.
Before attempting the installation make an inventory of the hardware components of your machine. Although the Ubuntu installation system will attempt to automatically detect your hardware, it may not always be successful. Probably the most important pieces of information to record are the IRQ and IO addresses for your ISA/EISA cards, if you have any.
If you're going to be doing the installation onto a machine, which already contains data, and you wish to preserve this data then make a backup! Ubuntu requires that there be some unused partition space on which it can be installed. Please note that this is not the same as having free space on your C: drive (assuming you're running DOS or Windows).
A typical desktop Ubuntu installation requires about 600MB of disk space, but this can obviously change depending on what additional software you intend to install, as well as the amount of data that you are going to be storing. It is highly recommended that you also review the installation documentation available on the Ubuntu CDs, as this will cover specific configuration problems in depth.
Ubuntu Linux is a community driven operating system like most open source projects. A way to get the most out of using the software is to become involved with the community. If you're running a Ubuntu system, it is definitely recommended that you subscribe to some of the Ubuntu mailing lists, you can subscribe to these mailing lists on this [http://lists.ubuntu.com/] page.
As someone looking after a Ubuntu system, you should at least subscribe to "announce" and "security announce" mailing lists. These are low volume, but they will keep you up to date with what's happening with the Ubuntu project, and, very importantly, about any security related information that becomes available.
During an installation of any operating system, it's a good idea to note down what it is you've done and what choices you've made, and possibly even your reasons. This can prove invaluable when reviewing a system, and especially if you have to re-install it due to a system failure!
Some of the other obvious things that you should do prior to an installation are to make an inventory of the hardware that the system contains, and then to check up online whether or not that specific hardware combination is supported by the operating system and applications that you are going to be installing.