This is the method to load plugin parameters in Joomla inside/outside the plugin itself.

The method is quite simple:

// generate and empty object
$plgParams = new JRegistry();
// get plugin details 
$plugin = JPluginHelper::getPlugin('system','languagefilter');
// load params into our params object
if ($plugin && isset($plugin->params)) {
	$plgParams->loadString($plugin->params);
}

Now you can use:

$detectBrowser = $plgParams->get('detect_browser',0);

for example to get a plugin parameter.