Starting with a fresh computer, grab copies of your documentation and your software. Install your software. Perform a standard operation or use case. How do you feel?
Who installs your product? What is the definition of an "average installer"?
Where is your software installed?
How is it installed?
What is the expected/required skill level of the installer?
How long does it take to install your software? Can lengthy portions be easily interrupted ?
Can you undo/remove what was installed?
How can you diagnose install problems?