Well organised, well-prepared content reaps many benefits. It keeps costs and timelines on track, and allows your designer to get on with the important work of making your content fabulous. Here's a quick outline on how to best supply your content. 

Pictures

Choose your pictures and group them in logical folders with the text they relate to.
If you have specific instructions for particular images, make sure they are clearly identified by their file names. 
Images should always be high resolution.

Text

Supply only final, approved, polished and proof-read text.
Never supply draft copy, unapproved copy or copy in which the spelling and grammar have not been checked. 

Captions

If you have large group photos where every person is named,  it is best to supply the captions as text files.