Resolution - All Colour and Greyscale images used should be 300dpi (dots per inch) to ensure quality in print.
Colour - For full colour print, images should be saved as CMYK ready for separation, unless you are using spot colours in Photoshop DCS2 format. Any RGB formatted images may produce slightly different results to your expectations.
Other considerations - Where images are used at different sizes, aim for 300dpi at finished size (i.e. an image at 150dpi and used at 50% size gives 300dpi). For ‘lineart’ or ‘bitmap’ images, (pure black and white) use 1200 dpi.
When saving in different image formats bear the following in mind; .tif gives the best quality; .eps allows for cut-out paths to be included; .jpg or .jpeg cuts down filesize but excessive compression will give reduced quality.