You will benefit from the structure of a catalog or the subject-specific nature of a specialized guide. If you find it, and you plan to use it again, bookmark it. The longest, most disorganized bookmark file in the world is still the easiest and most convenient way to get to resources you plan to visit more than once. Use a minute to save an hour. Always read the instructions for a site you aren't familiar with or haven't visited in a while.
Every tool has different rules.
Never forget that every search engine is different, which means every search engine has unique rules for constructing searches. Also, every catalog has its unique schematic and index vocabulary. In general, catalogs are often more available than search engines, and specialty resources such as Envirotext aren't as busy as general sites such as Yahoo. Particularly for search engines, check your spelling very carefully. It's almost always out there.