XBOX 360 2585
You make up a spelling and stick to it. :-) I think the most you can hope for is a set of consistent rules. Given a spelling, you should be able to pronounce the word, as long as you know what language it is and geographically where it is being used. You can't do that in English, because syllables like -ough have multiple pronunciations, but you can in Spanish.
Fitting new languages to the latin alphabet requires some flexibility and imagination. In Maori, there is a common sound that does not occur in English. It is usually spelled "wh", and used to be pronounced by English speakers as if it were English, as in "where", but it's now fashionable to pronounce it as "f". It should really be softer than "f", somewhere between the two. Fijian is really weird. If you have been there, you will have landed at Nadi, and called it "Nandi". Bula is pronounced more like "mbula", though the m is really just a buzz. C is pronounced as "th". So the name of the chiefly family Cakobau is pronounced "Thakombau". I don't know the origins of the Fijian conventions. Most of the mapping of sounds to letters was done by the missionaries, so you probably can't attribute it to a bad hangover.
XBOX 360 2586
Sorry, I had to snip. This is fine as long as you have an older human teaching a much younger human. (I'm still buttuming that this research that kids learn how to hear...
-- "What's life? Life's easy. A quirk of matter. Nature's way of keeping meat fresh."