Keep to one word to give the widest search results.
Don't use plurals
Try other words of similar meaning if your first try doesn't
results you were looking for.
If searching for a product type you can carry
out 2 different types of
search by using the same word in both the top and middle search
results of each search can vary to give you a wider search pattern.
You can search for a company name by just using
the top search line. Again
one word may do the trick