Also, many browsers still do not support frames so your pages may look funny to some of your customers. While you should definitely include links to other sites that could be useful to your customers, try not to over do it. You want to keep your customer at your site. Giving them too many links could be an unnecessary distraction. Also, large amounts of links clutter your pages.
Many pages now use words, phrases and links that are obscure and difficult to decipher.
No one should have to try to interpret your pages. Your visitor should be able to instantly understand everything on your page. Your page should have a clear layout without a lot of confusing and cluttered bits of information, images and links. Many people still prefer to see things in a hierarchical structure. An individual should be able to quickly find what they need and where to go to next.