Using the Msi Diagnostic logging to get detailed failure Information
msiexec /i Package.msi /l*v c:\Package.log
Where
Package.msi
is the name of your package
and
c:\Package.log
is where you want the output of the log
Msi Error Codes
Wix Intro Video
Oh and Random Wix intro video featuring "Mr. WiX" Rob Mensching is "conceptual big picture" helpful.