If your map is destined for print, check first with your print provider what format is best on their printing equipment.
On the whole, simple printing such as leaflets, cheap brochures and digital books will not need any special preparation and you will be able to output in a number of formats such as PDF, JPEG, EPS or TIFF. If the map looks reasonable printed from an inkjet or laser desktop printer then it should be ok for the bureau printing.
If your map is destined for CMYK printing, such as is often used for colour books, magazines and high-quality brochures, you will need to convert the file to CMYK before outputting. Find out if your print provider uses a colour profile and what overprint and choke settings you need on the map for elements such as text and road casings. In general we would recommend you use the Maproom CMYK black and greys swatch palette for any black text, and set black text to overprint.
When outputting for CMYK printing, your print provider will probably need a high-resolution PDF, EPS or TIFF format.
Maps are among the most complex forms of artwork that CMYK printers have to deal with. The highest quality print providers should provide guidance and settings specific to their equipment, plus proofs for you to check colours and clarity of detail and the opportunity to tweak settings before the map goes to press.