Now, seeing as I've got some funny hobbies, I needed to install an astrological symbol font. This has caused problems in the past. I located the correct file tree, created several required directories, copied a bunch of files, ran a couple of commands, and... voila! It worked. Just like that. No extra hassle.
I guess practise installing it on a couple of different systems earlier has been of some benefit. And I was smart enough to google up some decent instructions first.
(For the record, the correct local tree for installing packages in TeX Live on Debian Squeeze appears to be '/usr/local/share/texmf'.)