Note: Never defrag an SSD. SSDs don't store files contiguously, so defragging not only doesn't work, any attempt wastes precious write cycles. Instead...
TRIM your SSD regularly
Now this is a bit of a tricky one. Windows 8.1 Optimize Drives is smart enough that it doesn't defrag SSDs (make sure you're updated--this wasn't always true), instead sending a command that tells the SSD to perform its housecleaning. You may have thought that because your operating system supports TRIM (Vista and later, XP with drivers), that your SSD is continually taking care of its housekeeping chores. You'd be wrong. Instead, like a lackadaisical child, it says it will, then puts it off as long as it can. Any drive certified for Windows must respond to the command and actually erase formerly-used cells and consolidate data.
Alas, Windows XP, Vista, and 7 don't have this optimize command, so you're dependent upon a utility from your SSD vendor, if they even provide the function. Most don't. There's also a program called Solid State Doctor from LC Technologies that will force the housekeeping as Windows 8.1 does.
A workaround, if you own a copy of Windows 8 (updated to 8.1 for the optimize function), is to use Aomei's free Partition Assistant to create a Windows-to-go thumb drive. Use it to boot to it and run the Optimize Drive function on the host system's SSDs. It's my current MO for older Windows installations running off of SSDs.
Flush flotsam from the registry every once in a while
About the only thing really missing from Windows' own utility kit is registry cleaning and optimization. Microsoft says you don't need it. That may be true, however, there's a little neat-freak in a lot of us, as well as memories of the old days, where a bloated registry would actually take a noticeably longer time to load. That latter measurement may have been exacerbated by "watched pot syndrome."
Strictly necessary or not, I run CCleaner or the Wise Registry Cleaner, which also condenses the registry, regularly. Largely because I install so much software to test, but also because I get paid to ignore my own advice to see what happens. Both programs do a bang-up job of sussing out and removing unused registry entries. They also clean up your hard drive by deleting cached files, and unlike Windows cleanmgr.exe, they do so for non-MIcrosoft software.
Update your drivers and BIOS, maybe
There's a truism: If it ain't broke, don't fix it. If your PC is functioning fine, then the hardware drivers and BIOS are doing their job. If your PC is getting quirky, and you're noticing irregularities in, say, printing, then search out the latest drivers for the device in question. If the driver has been submitted to Microsoft, then Windows Update or the Update Driver Software function will find it for you. If not, visit the vendor's site for the latest and greatest.
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