I'm attempting to add many js files to my recently produced theme (I'm a new comer to wordpress theming ) I had been trying to get it done in by doing this :

function includejQuery() {
    if (!is_admin()) {
        wp_deregister_script('jquery');
        $jqueryPath = get_bloginfo('template_directory') . '/js/jquery-1.6.2.min.js';
        wp_register_script('jquery', $jqueryPath);
        wp_enqueue_script('jquery');
   }
}
function includeddAccordionUI() {
    if (!is_admin()) {
        wp_deregister_script('ddaccordion');
         $ddaccordionPath = get_bloginfo('template_directory') . '/js/ddaccordionUI.js';
          wp_register_script('ddaccordion', $ddaccordionPath , array("jquery"));
          wp_enqueue_script('ddaccordion'); 
    }
}

add_action('init', 'includejQuery');
add_action('init', 'includeddAccordionUI');

the above mentioned pointed out idea work all right to incorporate one file but when you include 2 file php goes into infinite loop (or even the page will not stop loading )

can there be much better method to include many js files ?

Make use of the action wp_enqueue_scriptswhen enqueuing scripts front-end. By doing this it's not necessary to see if you are in admin. Use admin_enqueue_scripts whenever you really wish to load it in admin. This is not merely to eliminate your bug, but additionally to eliminate the conditional. Also employ just one function and load all js from that function, to avoid possible duplication of code (for example your present conditional). If this doesn't work, it's nothing related to Wordpress and most likely is because of the js. A final recommendation is by using the incorporated js files, the usually suffice!

Codex page for wordpress_enqueue_script: http://codex.wordpress.org/Function_Reference/wp_enqueue_script