When doing a keyword search it's a good idea to try a number of different search terms and phrases. Don't be discouraged if your initial keyword search brings back too many, too few, or irrelevant results--you'll want to try multiple keywords, synonyms for your keywords, different combinations of keywords, etc. to bring back the best results.
For example, if you are looking for information about the dangers of texting and driving you may start out with keywords like: texting, driving, distracted driving, danger, cellphones, etc.
But you'll also want to try using synonyms for keywords (e.g. cellphones = mobile phones, smartphones, iPhone, etc.) and combining keywords (e.g. texting and driving, distracted driving, and danger, etc.) to get better, more thorough results.
Once you have brainstormed some keywords, it will be time to put a few together and actually try the search in a database or on the open web. You never know what combination of your keywords will be successful, so this step of the research process can take some time. Don't get frustrated if you try a few different searches with different keywords until you start to see results that might be useful. Here are some examples of searches we could run with the keywords above:
texting AND driving AND danger
texting OR cell phone AND driving
car OR driving AND texting OR cell phone