Combining keywords
Keywords can be combined to achieve results that better suit your question. By default you indicate which keywords should appear in the results (for example: java programming), but you can also indicate in most search engines or databases which words you do not want to see in your search results (eg: java -island) or that certain keywords must literally be next to each other (eg: "java programming").
Search filters and tricks
If you can limit the results to a specific time period, such as last year, you immediately know that your results are up-to-date. With the help of these kinds of filters you can zoom in much faster on results that are relevant to your question. Exactly how to indicate such filters varies per search engine. So if you use a search engine or database, find out what kind of search filters and other tricks it supports and how.