Internal linking is always a good practice from many perspectives. Apart from enhancing visitor usability,exposure to old posts & increasing visit length of users , contextual internal links also helps in improve a site’s rankings for targeted key phrases.

# Always try to use the same URL when linking to pages.
# It’s always best to use meaningful anchor text instead of using “click here” ” read here”. Try to target long tail keywords than targeting main competitive ones.
# Plan & link to related internal pages using targeted keywords as anchor text.
# Use breadcrumb navigation on sites that will link to other pages often.
# Try to lower the number of template links per page as Template links give less link juice than regular content links.
# Always Limit the number of links on any specific page to less than 100, this includes template navigation links too!
# For internal linking always use  absolute linking.
# Try to link to new content on the home page.
# Try to fix all 404 errors , for this you can take help of Google Webmaster Tools . Set up a 404 page with links to related content, refer to articles like # http://www.thesitewizard.com/archive/custom404.shtml , # http://www.4guysfromrolla.com/webtech/061499-1.shtml .
# Try to use static URLs always. A dynamic URL l is one that uses the $_GET function within the URL, e.g. http://example.com/?form=charts should be changed to http://example.com/charts. You can do this by using htaccess. For Changing dynamic to static URLs by .htaccess read this >> http://www.intelliwebtools.com/node/131 .

By following these properly will surely improve your website’s  over all usability & search rankings.