For those of you who read the ending first, or like things neatly tied up, here's a brief synopsis, automotive-style.
Break-in period--remove unwanted software, disable unneeded background apps
30-day service (once a month)--Optimize SSD (Windows 8.1 Optimize Drive or equivalent), run disk cleanup to remove unneeded files
180-day service (every six months)--Defrag hard drive, search for and remove duplicate files and empty folders
Inspect and fix as needed--Upgrade drivers and/or BIOS to solve hardware issues; update software if necessary. Watch installation dialogs for unwanted side-installs of software. Disable background tasks that are re-enabled after software updates.
Required tools: Windows' own utilities, plus CCleaner, Wise Registry Cleaner, OpenHardwareMonitor, and Passmark DiskCheckup.
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