Installation of Oracle is pretty simple. Some parts of it are confused by the intertwining of installation and creation of a database at the same time. In most cases I would personally suggest that you not create a database during installation. Creation is something better left to the Databate Creation Assistant (dbca) after Oracle has already been installed.
Something that can confuse a lot of sysdmins is the layout of files in an Oracle installation. You'll notice that often you'll see installations of Oracle in /u01 and data placed in /u02, /u03, and so on. But if you do a fresh install of Oracle it may not suggest that you install there. So then why do almost all DBAs install Oracle like that?
The answer is the OFA: the Optimal Flexible Architecture (note: optimal, not Oracle). The OFA was created by Cary Milsap in 1991 at the Oracle User's Conference. The OFA was an attempt to create a standardized set of conventions for Oracle file locations and file naming. The OFA has been widely adopted and is considered an Oracle "Best Practice". Other than just creating order from chaos, the OFA ensures that your installation will always be scalable to larger databases, new versions of Oracle, etc.
The installation guidelines, when combining the OFA and the Oracle installation recommendations, are detailed in the following sections.