theming a CCK input form How do I theme a CCK input form?
I tried the approach given in this page, but it is not working even after I clear the cache.
Here are the steps.

Suppose your content-type is: "account_registration" and you theme is "bluemarine".

I edited template.php and added this code:

function bluemarine_theme($existing, $type, $theme, $path) {
  return array(
    'account_registration_node_form' =&gt; array(
      'arguments' =&gt; array('form' =&gt; NULL),
      'template' =&gt; 'node-account_registration-edit'
    )
  );
}


I created node-account_registration-edit.tpl.php:

&lt;?php
  $form['buttons']['submit']['#value'] = 'Done';
  $form['buttons']['preview']['#access']= FALSE;
?&gt;


I cleared cache and edited a node, but the above changes are not showing up.
Your steps are right. I tested it on my local environment, and it works.

For example, for the content type "companynews", add the function to the template.php:

function garland_theme($existing, $type, $theme, $path) {
  return array(
    'companynews_node_form' =&gt; array(
      'arguments' =&gt; array('form' =&gt; NULL),
      'template' =&gt; 'node-companynews-edit'
    )
  );
}


Create the node-companynews-edit.tpl.php file and put the test code.

&lt;?php
  echo 'it works!";
?&gt;


Clear the cache, and access http://example.com/node/add/companynews: it shows "it works."

PS: You can also use hook_form_alter() to alter the form, and then use CSS to style it.