In different situations, you need a different approach to your searches and queries.
For instance, if you want to have a result list few in number, but precise in topic you might try to
1) focus your search terms on the title field only. Usually, if a term occurs in a title, one might expect it to be a key concept in a text too.
2) look through only the latest results by sorting: ‘Date, descending’.
Examples of publication titles:
If your search topic is still somewhat unclear or you know that the topic is “rare”, i.e. you won’t expect to find lots of results, you can search with one or two terms only in order to
1) see the frequency of the term in a database: if it’s infrequent, there is no need to add any limiting terms to the query.
2) browse the results to get an idea what there is available and how you could possibly refine the query.
If you need an extensive result of “all that is available” about the topic, you must
1) think different expressions and alternatives of a key concepts and
2) combine them to your query with the OR-operator.