There aren't any specific rules to follow for preparing an Adobe InDesign file to be translated in Redokun. However, there are a few simple recommendations that are worth following when designing an Adobe InDesign file that will be translated into different languages.
Optimizing a file before getting it translated is not only a good thing to do, but it also makes it easier to keep translation consistency across the document and across all your documents as a direct benefit of having 'cleaner' Translation Memories (TM).
Nonetheless, having cleaner and less fragmented TMs also have a positive impact on translation costs.
The same text in a different language might expand by as much as 30%, in your InDesign file, you should take care to prepare text-frames ready to accommodate the newly translated text.
You should use anchored frames when using creative design elements linked to a text (eg. images). This way, after the translation, the creative elements will be correctly placed. Not having to manually reposition your elements on the page can save hours on translating your file in many languages.
For different reasons you might need to change your document text proprieties. For instance, translating an English document to Chinese might required you to increase the size of the font in the Chinese language. Both paragraph and character styles allow you to be more precise in doing so and can save you a huge amount of time.
Use paragraph indent instead of spaces to add space around your text. Suggestions will work independently from the space used for formatting the text.
Use bullet lists, numbered lists, or lettered lists using paragraph styles or inline styles. This way, your sentences will be correctly formatted and ready to leverage your Translation Memories. Suggestions will work independently from the index of the sentence.
Be cautious while choosing the font to use in your publications. Not all the characters of a language might be available in a particular font. A good idea is to check if your font supports the characters like ü, ñ, etc. Generally, if the font you are using can render these characters, chances are it can render all the variances. Even if you have been cautioned, for Eastern European languages and character-based Asian languages (eg. Chinese, Japanese), the font will probably need to be replaced.