After you make your sitesearch easy to find, make it usable.
Text in the search box:
Keep some meaningful text in the search box and make it disappear on clicking so that the users can enter their search term without any confusion. If shoppers don’t find the desired product in the search results, they might search again with a slightly different search term. So, keep their previous search term in the search box so that they don’t have to type the entire search term again.
The submit button should look different from the input field and should either read "search" or have a search icon. Show results even when users press enter, but this doesn’t mean that you can do away with the “submit” button entirely.
Though search scope is not necessary for every eCommerce store, it is critical for large stores with wide range of products. Allow users to search within a particular category. Default your search scope to entire store rather than a specific category in order to avoid users searching within a wrong category.
Offer search suggestions as the user types in a query. A dropdown with common searches that will help reduce typos and avoid a no results found state. It’s even better if you suggest a few best-fit products along with thumbnail images and price of the products suggested. Land the shopper on the individual product page if he clicks on any product suggestion.