WP User Avatar preview for users

I’ve used this plugin in the past and have done this in the past.

$blogusers = get_users_of_blog();
if ($blogusers):
   foreach ($blogusers as $bloguser):
      $user = get_userdata($bloguser->user_id);

      <a href="https://wordpress.stackexchange.com/questions/160928/<?php get_author_posts_url($user->ID); ?>">
         get_avatar($user->ID, 70);  // 70 is the size of the avatar
      </a>

      if(!empty($user->user_firstname)):
        <h4>
          <a href="https://wordpress.stackexchange.com/questions/160928/<?php get_author_posts_url($user->ID); ?>">
            <?php echo $user->user_firstname . ' ' . $user->user_lastname; ?>
          </a>
        </h4>
      endif;
   endforeach;
   wp_reset_query();
endif;

Hope this helps!