like oil changes on a car, UK!? Yes, but easy peasy and not messy at all.

You'd have a hard time walking down the hall if it full of trash. It's the same with your computer when it's looking for files.

Windoze and programs generate tons of files, non of which are actually needed past 30 days.
BUT, windoze never throws them away. I've seen computers plugged up with files that were more than 5 yrs old.  Windoze built in Disk Cleanup utility (Start-Programs-Accessories-System Tools) doesn't throw them out either.
Windows is terrible a throwing "garbage" out. Many Programs are no better.

CCleaner will safely clean your computers hard drive of all the trash.
On that page is a download button for a pay for version (don't need it)
and right below is >> Download from <<  install the program.
It will run and all you have to do is click on "Run Cleaner"
Then close it when its finished.
It should put an icon on your desktop so you can run it every month or 2.

It also will clean out cookies so you may have to log into facebook or other social sites again. That's not bad. as Google Chrome and Firefox can save them securely. Not so with Internet Explorer, it save passwords in a plain text file.
BUT If you prefer to "Stay Logged In" you can scan for cookies to keep..
Have CCleaner run automatically on a schedule. How To here>>How To Geek

Another thing to do is Defragment the hard drive.
- - Windows Vista and later, finally, has automated this. Review it's schedule so you can leave the computer ON during the scheduled time, or change it to your liking.
XP, You will have to start the process manually  - -
What is Defragmenting This is akin to the librarian putting the books back on the shelves, in order, after the kids have left them on the tables in the library.
You can use Windoze built in Disk Defragmenter manually every month or two.
(Start-Programs-Accessories-System Tools) Optionally, Schedule a monthly defrag with Task Scheduler that's built in to Windows, just leave it ON at the scheduled times.

XP and previous versions, to automate this:
Defraggler and set it's built in scheduler to automatically run every month
(The computer must be ON at the scheduled time)
Get it from
Again, don't use the download button, free download is below it. (Download from
Install same way as above, set the scheduler to your liking, done.
Scheduling Defrag can be done with Task Manager but is easier to set up with

Install updates as soon as convenient after being notified.
Windows updates. Java updates. Flashplayer updates are all normal.
Updates to your browser. Hopefully you're using Google Chrome, Firefox or Pale Moon.
All regular updates are to secure your computer from hackers.

Don't install "Toolbars" needlessly. Many programs will want to install some toolbar along with the program you want to install. Watch, and read, all the dialog boxes that appear during install.
If there is a checkbox to install a "Tag-along" toolbar uncheck it. If you notice a toolbar appearing on your browser after installing software, that's not necessary for the software you installed, go to ADD AND REMOVE Programs and uninstall the toolbar.
You may also have to "Manage Add-Ons"  or "Extensions" in your browser to finish removal.

I would also uninstall the program that did not warn of a toolbar install but installs one..
I would also NOT install a program that requires a toolbar that's not necessary for the program.
These toolbars are no more than an advertiser wanting to know where you go and what you do there on the internet.

If the Security Essentials Icon is not green, or the icon of your chosen anti virus product is not "Normal" click on it to see why it's not. Update it or perform a scan as necessary to return it to it's normal color, and fully protected.

One more thing you can do. This may be a little messy, but not much. Unplug the power to your computer, Take off the cover. and use a vacuum on it's internals. Dust will plug the air movement and parts will overheat. The first clue that this may be happening is your computer slows to a crawl. It monitors it's own temperature. If it gets too warm, it will slow itself down so it produces less heat in an attempt to cool. Without air flow, it wont cool. I like to do this annually.

Thing to remember, a computer is DUMB. It's up to you to keep it operating well.

 LIFEHACKER has a "self repairing HDD" if you're a bit 'techy"