Getting clipboard text or images into a file normally requires some help from an application. Launch something, Edit > Paste, File > Save As, browse to the folder you need and enter a file name.
Pastextra is a tiny Explorer extension which enables pasting clipboard text or images directly to a file, no extra steps required.
The program has no installer, but it's easy to set up manually. Extract the archive to a safe folder, run Pastextra as an administrator and it registers itself on Explorer's right-click menu.
Once it's up and running, everything else is simple. Copy something to the clipboard, right-click in an Explorer folder and select "Pastextra". Copied text will be saved as a text file, a copied image as a PNG
If you decide you don't need Pastextra in future, run the program as an administrator again and it removes itself from the folder right-click menu.
Pastextra works as advertised, but won't necessarily save you as much time as you'd think. When pasting text, for instance, you'll need to open or switch to an Explorer window, navigate to your destination folder, right-click, select Pastextra, then maybe rename the file from its date and time-based default (like "20170217222136.txt").