Instead of using so many page numbers on your post page or having next and previous links, this plugin handles the pagination with a much more organized way.
If you look into the screenshots, it will be easier to understand what it does.
All you need to do is upload the plugin to your plugins directory just like any other Wordpress plugin. Then you need to add the following line to your single.php for paging your posts and page.php for your paging your pages.
mysinglepages(wp_link_pages(array('before' => '', 'after' => '', 'next_or_number' => 'number','echo' => '0')));
Pretty much all you need to add is mysinglepages() function around your page links function.
Click to download.