Well, this is on my experience, but for me at first, it's pretty tough, and can get my mind pretty busy.
Mostly what I have to do a lot of hardware repairs, which includes figuring out the problem, finding the tools and resources to replace any sort of broken material, and do the repair work from there.
Finally, I jot down the unit, the problem, and steps I took to fix it again, to have a sort of log. The log is handy in case there are similar problems; they serve as instructions to what to do.
As for troubleshooting, I don't do much of that, because most of the problems people at work have with their computers is as simple to solve as just restarting the computer. But otherwise, troubleshooting with software is basically what you can expect.
Sometimes I also help with the networking with the computers at work too. Some of the computers all run under a test system, so it's also my job to make sure everything runs smoothly without any lag or other problems.
I also help with establishing new software for those test systems. That can be more time consuming... but that's because we have to test each system to make sure everything works, and works consistently. If there's a problem, we gotta go aaaalll the way back and make sure we didn't make any codes wrong or if there's any program that has a flaw or something.
All in all, it's tough, mindful work at first, but after a while it becomes second nature, and it passes the time relatively quickly!