Although Front-end Editor tries to be compatible with as many themes as possible, there’s only so much it can do.

No wp_footer() call

Lots of plugins, including this one, rely on the wp_footer() call to include their JavaScript files. Open your theme’s footer.php file and make sure you have this line somewhere:

<?php wp_footer(); ?>

Using the_title() in the wrong places

A mistake I see in a lot of themes is code like this:

<a href="<?php the_permalink() ?>" title="Permanent Link to <?php the_title(); ?>"><?php the_title(); ?></a>

This causes all sorts of problems. You should use the_title_attribute() instead:

<a href="<?php the_permalink() ?>" title="Permanent Link to <?php the_title_attribute(); ?>"><?php the_title(); ?></a>

No id & class attributes for dynamic sidebars

If you want to have editable text widgets, you’ll have to change code like this:

register_sidebar(array('name' => 'My Sidebar',
	'before_widget' => '',
	'after_widget' => '',
	'before_title' => '<h4>',
	'after_title' => '</h4>',
));

to this:

register_sidebar(array('name' => 'My Sidebar',
	'before_widget' => '<div id="%1$s" class="widget %2$s">',
	'after_widget' => '</div>',
	'before_title' => '<h4>',
	'after_title' => '</h4>',
));

You can use <li>s instead of <div>s. The important part is id="%1$s" class="widget %2$s".