This code has to be pasted into your theme’s functions.php file. It can be customized to deal with custom post types, as shown on line 16 and after.

add_filter( 'default_content', 'pu_default_editor_content' );

function pu_default_editor_content( $content ) {
    global $post_type;

    switch( $post_type ) 
    {
        case 'post':
            $content = 'Default content for blog posts.';
        break;

        case 'page':
            $content = 'Default content for pages.';
        break;

        case 'portfolio':
            $content = 'Default content for your portfolio pages.';
        break;

        case 'products':
            $content = 'Default content for blog posts.';
        break;
    }

    return $content;
}

Credit: Paulund

The post How to pre-populate WordPress editor with default content appeared first on WPRecipes.