Too Many Search Results

Find better search terms. Think of terms that are more specific and try changing your keywords.
Use more search terms. Start with a small number of keywords and then add more terms or try different terms on the basis of your results.
Use limiters. Limiters such as date and resource type retrieve a targeted results list. For example, you may be able to limit your search to scholarly, peer-reviewed articles or to articles published within the past 3 years.
Search on different aspects of your topic. Try thinking about the specific aspects of your topic that you plan to cover in your paper and search for them separately. Then synthesize the information from different sources.
Do not use OR. Make sure you are not using OR between terms that mean different things; for example, plant OR nutrition. This search connector broadens your search by looking for either word rather than both and should be used sparingly.
Notice the default search options. By default, most databases search in the title, author field, abstract, and subject terms associated with the article. Experiment with searching in just the title or subject field in order to get more targeted results.
Narrow down your topic. Think about a more focused aspect of your topic or various angles of your topic. For example, if you are looking at the topic of problems faced in developing countries, you may want to search for information on problems in particular countries, programs that assist developing countries, or what defines a developing country.

Too Few Search Results

Try a subject database. Search in a database that specializes in a certain subject. If you need a database suggestion, try the research guide for your field. You may have to try several different databases; be flexible and persistent.
Broaden your topic. You may need to think more broadly about your topic. For example, if you are researching the impact of water treatment in rural Zambia, you might broaden your search. Break your topic into different parts and search them separately (e.g., the water crisis and then expand out to other countries), and then interpret and combine the information yourself.
Change your search terms. Replace the terms you use in your search with similar or related terms. Brainstorming keywords will be helpful for this.
Use fewer search terms. Each time you put in another search term you will get fewer results. Start with a small number of keywords and then increase the number.
Use fewer limiters. Try using only limiters that are absolutely necessary. For instance, if your assignment requires only scholarly, peer-reviewed articles, use the limiter for peer-reviewed articles but nothing more.