Software issues are the main cause of most computer problems. There are so many different software programs, all written in different code, all trying to talk to each other and work together without having conflicts. Inevitably, just as in human interactions, there are conflicts, and these can cause overall computer issues.
The best way to avoid these types of problems is to keep track of what you install on your computer.
Watch how your computer behaves after you install a new program. If your computer begins to slow down or act strangely, you can troubleshoot the issue by uninstalling that program and seeing if the problem is resolved.
That's really the best way to view computer troubleshooting, in my opinion. Know your computer, and keep track of anything new you do with it. Then when a problem shows up, ask yourself, "Since the last time my computer was working fine, what changes were made?" In this way, you can quickly narrow down the possible causes to the most likely culprit.
Computer troubleshooting is easier I think, if you know how the computer works, and especially what happens when you turn it on. If you have that information, then you can use it to troubleshoot most Windows problems.
For example, let's say our problem computer won't start. It gets to the Windows splash screen and just stops. Because we know what a computer does when it first starts, and how it gets to that Windows screen, and what it is supposed to do once it gets there, we know immediately where to go to look for the problem.