A good internal link structure represents a sitemap of your site . An internal link structure can be made by placing all the links in tidy menu . Another method is to have the home page link to every page and then every page links back to the home page .Assuming that your directory structure is
the same depth for each page then each page will get an equal share of the PR.
But some times you don't want every page to get the same PR .You may want to downgrade some pages such as you "contact us" page. Would just be a waste of PR to have a high ranking page for your email address. Another (rather cruel) use would be to lower the PR your links page for link exchanges. So that you don't leek PR to them too much.
To do this you just reduce the number of links to the page to be downgraded.
So if you have every page linking to each other but the "contact us" link only appears on the deep pages, not on the home page. This reduction in the number of links to the downgraded page will result in less PR going to that page plus since the page is not linked to off a high PR page like the home page but rather off other deep pages, it get's an even smaller PR yet again.
Another way to adjust the flow of PR is the position of the links within a page. Links at the top of the page's html will get more PR through them than links at the bottom of the html. In a tabled layout, the left column is usually at the top of the html while the right column is a the bottom. So links put on a left hand menu will get more importance than links placed on a right hand menu. So links to important pages go to the left and unimportant links go to the right.
You can also use markup to show importance and unimportance of some links to others. Putting a link inside <em>, <b> <i> or <h1> tags will mark it out as more important than normal. In the reverse, wrapping a link inside <font size="1"> tags will make them less relevant to the SE spider.
Develop Best internal link structures for better search engine rankings.
Internal link is another important factor for good search engine rankings, Search engines like the internal structure to be theme based to determine the relevancy of a site, Points to remember when you are making your internal link structure strong: