This metacrawler covers 13 Web search engines, more than two dozen on-line news services or other types of sources, and sorts the results by the search engine that found them. It's a good starting point to see which one will retrieve the most. This metasearch site compiles the results from Yahoo, Excite and five other search engines. It is a good way to get a quick view of what's out there, but it is difficult to refine searches. Try this site for the latest information on many search engines and directories.
Most search engines provide some basic and advanced search tips.
Some let you refine your search as you go along, by prompting you with suggested terms, or by allowing you to add your own. Always check each search engine's Help screens for specific instructions for that system. Remember that search engines vary in their coverage, their features, and their mechanisms for choosing the most relevant sites for your topic. Try several to get the best results. Also keep in mind that search engines are always changing, and new ones are being added.