Helpers

My AppHelper usually inherits the Tools MyHelper:

App::uses('MyHelper', 'Tools.View/Helper');

class AppHelper extends MyHelper {
}

Furthermore, you can use aliasing to use any of the Tools plugin helpers as if they were normal App helpers:

App::uses('MyController', 'Tools.Controller');

class AppController extends MyController {

	public $helpers = array(
		'Session', 
		'Html' => array('className' => 'Tools.HtmlExt'), 
		'Form' => array('className' => 'Tools.FormExt'), 
		'Tools.Common',
		'Tools.Format', 
		'Tools.Datetime', 
		'Tools.Numeric', 
		'AssetCompress.AssetCompress',
		...
	);

}

Be careful NOT to set those aliased helpers in other controllers' or plugin controllers' $helpers properties then again without the verbose alias definition. This would effectively reverse the aliasing again. It's best to always only specify the additional helpers in extending controllers:

class PostsController extends AppController {

	public $helpers = array('SomeAdditional', 'PluginName.SomeOther');

}