Adding string to languages?

My apologies if this has been asked before or is documented in the wiki somewhere, but after 20 or 30 minutes of looking I didn't find it anywhere. (Admittedly I have only had one cup of coffee this morning)

I'm working on a patch that will require a new string in the languages files, what is the protocol for adding a string? Should I try to keep it near other related strings if there is a free one or do I just take any free one I can find? Also is there a procedure to notify translators when the string files change?

Thanks

there's a few comments regarding reservation of ranges (in the english strings.xml). respect those, then just grab a random string. translators watch the commit log, no need to worry about that.