If you embarking on a multi faceted marketing campaign it’s a good idea to involve a copywriter in the early stages.
For example, I have in the past been asked to prepare pieces for inclusion in leaflets and brochures and have written them as per my brief including all the relevant information. Simultaneously a graphic designer has gone to some trouble to create beautiful pieces of artwork and supporting imagery but has not allowed sufficient room for the copy. This kind of thing can lead to unnecessary costs in terms of redesign and/or rewrites.
By involving me at an early stage I can liaise with and work alongside graphic designers, art directors, advertising executives, marketing consultants, web designers or whoever else you have in your team to ensure all your marketing campaigns are integrated and that you are delivering a single clear message to your existing, new and potential customers.