Code example for this Forrst post: http://forrst.com/posts/A_more_elegant_way_of_doing_this_PHP-GCM

query.php

<?php 
/**
 * Use WP_Query, not query_posts.
 * get_posts is an OK alternative, but is basically a 
 * wrapper for WP_Query; and using WP_Query directly lets us
 * use `$my_query->the_post();` which sets up the global $post 
 * object -- so that we can use the `the_*` functions.
 * http://codex.wordpress.org/Class_Reference/WP_Query#Usage
 */
$my_query = new WP_Query(array(
    'cat' => '21',
    'orderby' => 'CPTOrderPosts'
));

while ( $my_query->have_posts() ): $my_query->the_post(); 
    /**
     * Use post_class to output the classes so that you also get
     * all the classes WP attaches to a post, like the post-type, 
     * categories, format...
     * http://codex.wordpress.org/Function_Reference/post_class
     * 
     * `$my_query->current_post` is kept track of in the query itself,
     * so no need to create a `$i`.
     */ ?>
    <li id="wh-<?php the_ID(); ?>" <?php post_class( 'post-' . $my_query->current_post ); ?>>
        <a href="<?php the_permalink();?>"><?php the_title(); ?></a>
        <?php the_content(); ?>
    </li>
<?php endwhile; 
/**
 * When you're done with the $my_query info, reset the global post.
 * This sets the $post object back to whatever page you're on, so
 * the `the_*` functions will return the main query's info.
 */
wp_reset_postdata();