With a mock building tool can greatly reduce the planning time and get a clear picture of what information will be needed on each page.

 

 

Here are a few of them:

 

Pencil - free and opensource tool for making diagrams and GUI prototyping http://pencil.evolus.vn/en-US/Home.aspx

 

Mockup Builder - http://mockupbuilder.com/

 

Cacoo - http://cacoo.com/

 

MockFlow - http://www.mockflow.com/

 

LucidChart - http://www.lucidchart.com/

 

HotGloo - http://www.hotgloo.com/