How Many Pages Make a list of ALL topics to be covered on the site. Take that list and break it down into the number of pages you will need to cover the topic well. Use a word processor for your text, as it would be on individual pages. Try to keep the length of the pages no more than two or three full screens. What you see when you look at the initial page without scrolling is one screen.
Visitors lose interest easily if they have to scroll very far.
I use Microsoft Excel to maintain a list of what goes on each page. This helps when you want to get organized for upgrades. You know what is safe to delete and what has to be saved. As the site ages it is easy to forget what a particular file is for if it isn't used often. Now that you have a good idea how many pages will be on the site, it's time to decide on a navigation system.