You may want to broaden your search. This can be accomplished by shortening or generalizing the words you search for. For example, a search for 'tall shirts' could be broadened by searching for 'tall' or 'youth running shorts' could be broadened to 'youth' or 'youth.shorts'.
If you are entering a part number, do not include any hyphens or other punctuation marks. You may even try using a portion of the number if it is a long one.
Spelling does makes a difference. Be sure to check for spelling errors as this will affect your results.
Mutations of a word also make a difference. For example, the word 'accessory' will return different results than 'accessories'.
Plural makes a difference too. Adding an 's' may impact results. Often it is better to search for the singular.
The search is not case sensitive, so you can type in all lower case, all caps, or any mixture.