This one's more for larger sites - but it could apply to smaller sites.
Ensure that every page has a search box, and place it at the top of the page. Make it obvious it is a search box, and try to use the word 'search' or 'go' for the button (I prefer search as it tends to be more intuitive for the user).
Make sure the search box is long enough so that the user can see the search terms they are entering into the box.
There are both benefits and problems when considering implementing a site search feature.Benefit
: Helps user find what they want.Problem
: Could lose user due to poor or missing search results.
For example, most site searches work by indexing the websites visible text.
Let's say someone wants to find an address on a site that doesn't have the word "address" located anywhere, but does have the company address listed. The search result will yield zero results, even though the information is truely there.Are you feeling the frustration?Benefit
: You can gather valuable information by capturing visitor search queries. Those search logs are a gold mine of keyword and search-ability information!
As you can see, there are many potential benefits and issues by using a site search. Most don't think through these issues before diving into this arena.Where am I going?
Another usability best practice would be to define the purpose of your website. I see so many sites that are nothing more than a blob of information that someone slapped on the Internet. Site owners seem to pray that you'll figure out where to go and what to do next.
Define a few goal/target pages...and then help the visitors get to those pages.
If an e-commerce site's goal is to sell products, make the target page the "Thank you for purchasing our product". I think a mistake that is often made is defining the "Buy now" page as the the goal/target. This would be incorrect, because if your form or applications are difficult to use (or broke) - you may be losing customers at the form - and never know it. But, if you define the target page as the "Thank you" page, you can measure true success.Example
100 people get to the "Buy" page, but only 10 make it to the "Thank you" page. There are issues!