There were numerous huge mistakes:
(in chronolical order)
Electing and mor importantly re-electing Bush as president
McCain voting with Bush over 90% of the time
Choosing McCain as nominee
Abandoning their simple yet effective experience criticism by choosing Palin as veep
Having no real strategy after national convention
Doing nothing but dishonest and sometimes vicious smears, instead of addressing issues - same thing that got Hillary
Saying the fundamentals of our economy were strong
Not taking responsibility for the voilent mobs they were creating
I highly recommend this article: NYT: Near-flawless run from start to finish - The New York Times
(in chronolical order)
Electing and mor importantly re-electing Bush as president
McCain voting with Bush over 90% of the time
Choosing McCain as nominee
Abandoning their simple yet effective experience criticism by choosing Palin as veep
Having no real strategy after national convention
Doing nothing but dishonest and sometimes vicious smears, instead of addressing issues - same thing that got Hillary
Saying the fundamentals of our economy were strong
Not taking responsibility for the voilent mobs they were creating
I highly recommend this article: NYT: Near-flawless run from start to finish - The New York Times