The best overall search strategy is to start general and get more specific as you go along. This applies on a number of levels.
By the time you're ready to search, you should have a sense of how many and what types of sources you need to complete your assignment. But where should you search for them? There is no single place where you can find everything you need. Different types of sources are found in different databases, so plan to do at least 2-3 separate searches to cover your bases.
UNM University Libraries subscribes to more than 450 databases! They come in many forms, and have all sorts of content in them, but in general they can all be searched using the same basic skills. Follow the "general to specific" rule here:
Strategy 1: upgrade your keyword searching. Pick out 2-3 specific words or phrases. Get rid of any filler words. Databases function using only the information you give them; they can't guess synonyms, and they don't understand which words are important and which aren't. They will not correct your spelling errors.
Strategy 2: enhance your keyword searching using Boolean operators and other advanced tools. Boolean operators, originally from logic and math, are words we can use to "glue" our keywords together in different ways.
Subject headings are used to some degree in all databases to describe and categorize sources. Most sources that are included in a database have been tagged by humans with "controlled subject terms" that describe the basic topic(s) of that source. This means that experts got together and chose specific terms to describe concepts (for example, sources referring to soda, pop, cola, etc are all found under the heading CARBONATED beverage in Academic Search Complete).
The quickest way to find subject headings is to do a keyword search and check the subject headings on any article that seems relevant. Clicking on the subject term will take you to the full list of sources tagged with that subject heading.
Subject headings are useful because once we find the right one, it will lead us to all of the sources the database has on that topic, whether they showed up in your original keyword search or not. They are much more accurate than keyword searching, if you can figure out how to use them.