We're lucky to work with an open-source project: closed-source projects sometimes do not even give the translators any chances to test their translations in the game! Make use of this.
Remember to use UTF-8 EVERYWHERE.

By the way, here is another question: should we use our native typography when translating the game or should we limit ourselves to the "forum minimum" -- that is, use "programmer's quotes" instead of «our» “native” »ones« and use — native – dashes instead of their - poorly-looking -- replacements? It's a question of Console Style vs. Book Style.
If we want to keep the game "console-looking" (or if the game font does not support all these characters), then Programmer's Minimum it is.
If we want to make it more "book-ish", then...

I'd keep it simple, and use Programmer's Minimum. We'd have to use some Wesnoth-style graphics to be able to use proper typography.

But I digress, and digress heavily.


The next thing you should do is be able to compile Crawl on daily basis.
It should be much easier to do in Linux flavours (especially Debian/Ubuntu and, I think, Arch).
Read the guide on compiling the game and try assembling a Stable version and a Trunk version (both Console and Tiles) from the source codes.
If you cannot do that, ask somebody who can (and who is not an admin: they already have a huge load on their shoulders).