Ensure that your Theme supports Post Thumbnails, and that the client sets a “Featured Image” for each post. Then, combine the_excerpt()
with the_post_thumbnail()
, e.g. like so:
<?php
if ( have_posts() ) : while ( have_posts() ) : the_post();
?>
<div id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
<div class="featured-image"><?php the_post_thumbnail(); ?></div>
<div class="post-excerpt"><?php the_excerpt(); ?></div>
</div>
<?php
endwhile; endif;
?>
Then, just use CSS to style according to your needs.