Easy one: this function redirects any user that hasn`t administrator capabilities to que home page of your site, if they try to access wp-admin/

add_action('admin_menu', 'redirect_dashboard');
function redirect_dashboard(){
	if( !current_user_can('level_10') ){
		if( preg_match('#wp-admin/?(index.php)?$#', $_SERVER['REQUEST_URI']) && ('index.php' != $menu[$page][2]) ) wp_redirect(get_bloginfo('url')); 
	} 
}

Just include it to you theme’s functions.php.