On all document types that needs translation (probably all of them, right?), add a new content tab for each language. If there already is a tab for content, because you are adding localisation to an existing document type, let this tab contain the translatable fields for the initial – “master” language. Each tab should be labelled after the language it is to contain. You can write the full language name here, if you please; no need to use the language-code (except perhaps for saving screen space).
For each field that needs translation, add the same field to each language tab – but call the alias for each language that is not the initial language, the field name plus “_” plus the language-code. Thus, if a text field of type “Textbox Multiple” is called “abstract” on the initial language tab, make another text field of type “Textbox Multiple” on each language tab, alias-naming each “abstract_XX” where XX is the language-code.
Take care, that the fields names are exactly the same and placed in the same order. This will make translations easier for the editors.
Fields that does not need translation (images, links, metadata and so on), you can either place on the content tab for the initial language, or perhaps even better, move them to a “common” tab.
Example: An article contains 4 fields, of which only the “author” should not be translated. The rest are repeated for each tab, adding the language-code postfix to the Danish and Swedish tabs field aliases.
When the editor creates a new document of the localization-prepared document-type, he will have a tab for each language, and fields arranged under each tab, with the same names and order across the tabs.
Example: The article from the example above, as seen in the document editor. The initial language also contains the “Author” field. Otherwise, the two tabs are identical in structure and labels.