How often have you looked at a site only to find that it looks like the inside of someone's brain in the middle of a migraine? Too many sites fall victim to the temptation to animate everything—animation is a secret ingredient that can make the most impact when care has been taken over its use.
So, what makes a good animation? This will depend on the context of the site, but there are some good tips that every designer should follow:
Don't overdo the attention grabbers—visitors want to feel in control of their browsing experience, so plastering a subscription dialog just when they reach the information they need is a big no-no! Use it to highlight something they might have missed, not to distract them.
Animation works well when it is used to highlight context and navigation features; a good example is an animated sidebar that provides useful local information. The contents of the sidebar will change frequently, so the use of animation will help to point out new information...