This set of pages has information on how to do library research. In all cases, once you have located sources, be sure to evaluate them, using the evaluation guides.
Don't take things for granted--your Help Desk assistant is probably not taking your course, and does not have the same background you have.
Staff may not be familiar with the exact subject. Widespread knowledge of subjects cannot be assumed. Ask if the library staff person knows what an "umsquitch" is. If your question is "what is an umsquitch?" be prepared to provide as much information as possible--did the term come up in a scientific paper? A general newspaper? A psychology textbook? This information will help the staff member look up the definition with you. You may be referred to a librarian who is more familiar with the subject area of your term.
If you are looking for the complete citation to an article or book, it is always helpful to know the subject area, exact or approximate year of publication, and where you acquired the information you already have.
If there is any possible doubts that you know about as to the subject area, explain. "Jane Doe" is a writer, a painter, or a politician.
Are there alternative possibilities? Will "A" serve as well as "B"?
Ask direct questions--how many units of x? How often? Weekly? Monthly? Annually? Instead of how much, ask for percentages, dollars, miles, pints, etc. There may not be a reference book with the exact answer, but at least the staff member will know what you really want and will look for it; you may need to convert some answers (kilometers to miles, for example). Sometimes you will be shown alternative information--remember, not every piece of information is found in every possible arrangement. Also, if the information has not been collected, it can't be found.
Clarify. Profits or prophets? Watered stock--finance or cattle? Specific kinds--soap: laundry, facial, dish?
Explain how you are using the term, and then ask your question.
Understand the issue/question yourself--unless that is what you are asking about.
Know the spelling of key terms, if at all possible, or be willing to look them up with the staff member.
Words: does the word mean what is intended? Are there any other meanings? Also, is the meaning clear in this context? There could be more than one pronunciation. Be willing to spell or write your key words or terms.
How you ask the questions may mean something different, so be sure to say what you mean.
If it will be helpful, tell a bit about your research background: have never used a library before, have never done research, have used other libraries, know how to search the online catalog, don't know how to search the online catalog, are a student in X course.
Tell how much you want to find out. What sort of time frame do you have?
You may be referred to another library or agency that might have the information you need.