This cannot be overstated. When we write it must be as straightforward and as understandable as possible. Make sure your copy is written in plain terms. It is also safe to assume that translated language will be longer than the English. This is especially important to keep in mind when writing microcopy for our products. This rule not only helps translators, but it also helps users who interact with our software in a language that is not their primary language.
On this note, avoid unnecessary metaphors or references. Part of writing for translation is to consider cultural differences. Turns of phrase or slang in one language does not necessarily translate. It’s best to not get too fancy when you write.