There is a script getnonfreefonts available that makes it easy to install a number of fonts including URW-Garamond. The directions are found at http://www.tug.org/fonts/getnonfreefonts/. On my Ubuntu system with TeX Live, I was simply able to run the following in the terminal to download and install the script:
# download installation file and install script
wget https://tug.org/fonts/getnonfreefonts/install-getnonfreefonts
sudo texlua install-getnonfreefonts
# optional: clean up the installation file
rm install-getnonfreefonts
This installed the script getnonfreefonts to /usr/local/bin and the corresponding documentation to /usr/local/share/man. On my system the shell looks for executables and documentation in these two locations so I was simply able to run the following:
sudo getnonfreefonts --sys -a
Running getnonfreefonts --sys -a downloaded all of the available fonts (of which URW_Garamond is one) and put them in the appropriate directories in my texmf tree. This took about a minute. After that, the downloaded fonts worked using the appropriate \usepackage directives!
Edit: as per a comment, use getnonfreefonts-sys rather than getnonfreefonts (edited above). See Why shouldn't I use getnonfreefonts to install additional fonts? Why shouldn't I use updmap when installing or removing fonts? for why.
Edit 2: it seems that for newer versions of getnonfreefonts there is no executable getnonfreefonts-sys and you should use the --sys option for getnonfreefonts instead.
microtypeyet. The second route requiresotftotfmand this worked fine. I've described the implementation details of the ```otftotfm`'' route in LaTeX and Friend but for a different typeface: Nexus. – Nov 22 '12 at 08:45