How to exclude certain particular files from Spotlight?

I know that you can exclude entire directories or files with a particular extension from Spotlight. But can I hand-pick files not to be searchable by Spotlight, preferably with a file system flag? I am a writer and keep old copies of my drafts but they muck up Spotlight with lots of search results.

Solution 1:

.noindex

One of the fastest ways to hide a file or folder, from Spotlight, on the fly is to add the .noindex extension to the end of the filename or folder. The simplest way to get those files hidden is to create a folder, preferably named something innocuous, and add the extension to the end of the name. I’ll end up with a folder named “Nothing to See Here.noindex” or something similar.

Hide just a single file

Select the file to be hidden. Right-click and select Get Info, or click Command+I. Find the Name & Extension field, and replace the current extension with .noindex. When prompted to confirm that I want to change the extension, I agree. Now my file is properly hidden from Spotlight search.

Finlay:

Finder won’t know what to do with my file anymore, though. Look to the drop-down labeled Open With, and select an application to handle the file. Be careful of setting a single application to handle all .noindex files, as many different file types may be hidden from Spotlight, and OS X sometimes creates .noindex files itself