Here are some hints:

1. Double check spelling.
2. Try both singular and plural forms. For example, "knife" if "knives" produces incomplete results.
3. If the only difference between singular and plural is the letters "s" or "es" then always use the singular form. For example, always use "ring" instead of "rings".
4. Use fewer words or letters to produce more complete results. For example "velvet" instead of "velvet ribbon" may produce a more complete list as might "clamp" instead of "clamp-on".
5. Always use a minumum of 3 letters in a search.
6. When searching use no punctuation such as ",?,. and no boolean terms such as "AND", "OR", etc.