The project ValTrad is developing a new section for the Spanish style book of the book production company Aibana, located in Barcelona. Currently the style book does not include recommendations regarding lexical usage, among other areas of language use. Our work involves: 1) analysing the corrections introduced into a corpus of professional translations into Spanish, 2) systematizing those corrections according to linguistic and translational criteria, and 3) elaborating a set of categories to be used by  translators, copyeditors and revisers working for the company, illustrated with real examples from previous work.