Just as important is making sure that there is an alternative way to get the information that is being presented by the script or applet. Beware of building pages that require fancy plug-ins. Plug-ins take a long time to download and are not available for many machines. By requiring plug-ins you will be excluding a percentage of your viewers. Label with the title or name attribute.
Frames are attractive for the beginner to utilize, until they have seen bad frame pages.
When used incorrectly they can prevent people from navigating your site or even reading your basic information. More frustrating are the frames that linger after you have left the site. Be aware that most people dislike using pages with frames and that should you decide to use frames it will require special care when creating any link on any page in your site. Also most of the older browsers, independent browsers and assistive technologies can not work well with frames. Again you might be excluding a portion of your intended viewers.