On the bottom of comments.php I use the following code:
<?php comment_form(array('comment_field' => '<p class="comment-form-comment"><label for="comment">Comment</label><textarea id="comment" name="comment" cols="45" rows="8" aria-required="true"></textarea></p>', 'comment_notes_before' => '<p class="comment-notes">Your email address will not be published. Required fields are marked *</p>', 'comment_notes_after' => '', 'title_reply' => 'Leave a Reply', 'title_reply_to' => 'Leave a Reply to %s', 'label_submit' => 'Post comment', 'cancel_reply_link' => 'Cancel reply' )); ?>
It’s not perfect but the best I have.