The problem
Whilst trying out new Conky config files on Crunchbang Linux (wiki to follow about this) I had a few problems that turned out to be fonts that were needed that I did not have installed.
A quick web search later and the fonts were downloaded, but how do I install them so the system knows about them??
Background
Fonts in general are stored within the root file system, but an extra folder is in the /usr/share/fonts in which extra fonts can be added. This is fine until you reinstall and then you have to add them all over again. A far better option is to add a ".fonts" folder in your home folder and place extras there, this way when you reinstall, as long as your home folder is a separate partition (which is a very good idea), they will still be there in the new install.
If you cant see any folders with a preceding . then make sure you have the show hidden folders ticked in your file browser.
The Solution
Once all the new fonts have been copied there, open a terminal and type
#> sudo fc-cache -f -v
followed by your password, this forces the system to look for new fonts and install any found.
Hope this helps, as it took me quite a bit of searching just to learn how to do this seemingly simple task!
These instructions are for a Debian based system (Ubuntu, Mint, #Crunchbang) but should work for most Linux distributions
As usual thanks go to the folks on the ubuntu forums for their great wit and wisdom. :O)