Always have a package.d for your package, even if it contains no declarations.
Always use a module declaration on all modules, and always put a comment on it.
Always put a ddoc comment on a public decl, even if it is an empty comment.
Want an index.html generated? Run adrdox on a module index; (this is a filthy hack but it works)
adrdox will not descend into undocumented entities, so a missing doc comment on a top level
declaration will make all effort in documenting inner items useless. If you do not document
a module declaration, the whole module is skipped!