The W&M Library looks small from outside, but the collection of books is massive (part of the library is underground, and we use high-density shelving).
Start with your topic. Example: I'm interesting in the consumption of goods in the British World during the colonial period.
British Empire OR Great Britian
Consumption OR Trade
Results aren't great. Try "Great Britian" AND consumption
Narrow the results with subjects or publication date.
I see "Great Britain" AND consumption are both subjects. Narrow the search and find fewer results:
If you already found books you like on your topic, search them in the catalog to see what subject headings they use. This will point you to new books!