Quick and dirty troubleshooting

Haha, I remember so many unplugged computers, telephones and printers complaining about broken hardware... Plugging stuff in is the solution about 30% of the time =)

I strongly agree with brian ;-) and here's why: because if trashing the preferences is NOT the answer, then congratulations--you've just lost all your prefs for that app! (Yes, you can back them up, and then restore them if needed, but then you've done the same amount of work that creating a new user would be, so there goes that argument.) Not a huge deal in the case of, say, Preview or TextEdit, but it takes a LONG time to get Photoshop or TextWrangler set up just the way you want it. The world of "problems" is HUGE and I'm a believer in using logic to find the true cause, not just using a shotgun approach and hoping that something that you did fixed it. (Because what it it's an intermittent problem and you do SOMETHING and now it's working--is it working because you fixed it, or is it just working AT THE MOMENT and the as-yet undiscovered problem is still lurking out there?)

If you install something and it's not working, or working sometimes and not others, then yeah, go ahead and get the newest version, check for system updates, etc. If it's something you've used every day for two years and all of a sudden you can't print or export or copy/paste then you should try to find the root cause. I've had programs stop working and then discover that it was because the hard disk was full. Another time, I found that Photoshop would crash if you had something--even TEXT--on the clipboard from Entourage.

As for updates that break things, that doesn't happen often, but when it does, it's usually a BIG problem.
http://www.google.com/search?q=quicktime+update+breaks
QuickTime, in particular, has broken quite a few things in recent years, even Apple's own Final Cut!

Troubleshooting is a huge world and is not something that can be addressed fully in a short article. There are literally thousands of things that can go wrong and many ways in which they can go wrong. There are different steps to be taken if you're having a problem with an app you use every day versus one you only launch occasionally, one that depends on your Internet or network settings being set a certain way, or one that stems from the relatively rare but very severe cause of "hardware issue." I'm just a believer in doing things with the least impact first and that depends, in part, on your environment. For me, I've already got an account on my Mac for guest use and I've usually got a lot of things open at once, so switching to another user is much, much simpler than rebooting. And if rebooting DOESN'T solve the problem (and it doesn't, as often as not) then, as you were saying, you've wasted a step and done nothing.

The fact is, in ANY troubleshooting, every step is "wasted" until you find the problem, (kind of like how things are always in the last place you look) so all you're doing is choosing which of two equally "wasteful" steps you want to do first. (And they're not truly wasted, since any smart troubleshooting step will narrow down the list of potential causes.) If you want to trash your prefs first, fine, be my guest, but that's not my first choice.

From my experience, if an app is working weirdly, the #1 fix is to delete (actually compress them, then trash the originals) the preference files for that application.

You can find the preference files for most apps in
~/Library/Preferences/com.CompanyName.Appname

(where ~ means your user home folder)

Restarting the app will force the app to create pristine preference files.

Or try a visual flow chart of the same:

http://xkcd.com/627/

It would have been great if he would have put those steps into a meaningful order. Testing as another user is one of the FIRST things to do because it shows if the problem is at the system/app level or in the user area. If it's in the user area, you can move onto things like trashing preferences, caches, etc. If it's in the system/app area, then you can do things like check for updates. Also, the steps vary depending on the problem. If it's a case of "it worked yesterday and doesn't work now" then you probably DON'T need a software update--in fact, updating will just introduce NEW variables (and possibly new problems.)

#9: Creating a New User is always a great idea to see if its the App or something you messed up in your own settings.

Quick flashback to The IT Crowd, "Hello, IT, Did you try turning it off and on again? Is it plugged in?"