The list of lessons from this campaign for Republicans is long. But aside from ideology, the particulars of John McCain’s personal limitations, and the failures of his staff, it would be good to keep in mind the arguments and tactics that didn’t work.
The electorate really doesn’t care about “experience.” Voting with a unpopular incumbent president most of the time resonates, and a relationship with a cast of vile characters doesn’t, unless you can show why it matters. The petty back-and-forth squabbles, the gotcha web ads, and the gaffe of the day are utterly lost on most voters. Unless you get the really big things right, and make the most of the times when everyone is paying attention (e.g. react to the financial crisis, the Convention speech and the debates), all of the day-to-day small stuff is just that–small stuff.
Finally, screaming at the MSM is intensely satisfying, but useless. Republicans are entirely justified in calling foul on the appalling media bias. But so what? Republican candidates still have to run a campaign.
None of this is particular to McCain or to the issues in this race. The danger for Republicans is to ignore these lessons in favor of the “we were doomed” or the “McCain ran an incompetent race” analysis. Either of those takes may be accurate. But the lessons of 2008 are still there to be applied in a race in which the GOP candidate might not be saddled with an incompetent campaign.