One of the mistakes I frequently see in "professional" websites is a lack of consistency across the entire website. Different pages might be laid out slightly different, or they might have different background images. In extreme cases, I can't even tell if I'm on the same website, aside from looking at the actual address of the site.
This lack of consistency across the site shows a lack of professionalism. Even if all your other business material is extremely professional, a website with that problem can bring your whole business down. Potential clients who look at it will have a lesser opinion of your business as a whole.
There are several things that should be the same across all of your site.
Tim is the author of Webifiable - Plan, create and maintain your web site the right way and is owner and senior web designer at T&S Web Design. He also maintains a blog with free website advice for small business owners, GetASiteOnline.com.
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