1) Start with Oxford Art Online to get basic information and main ideas, including:
* Because Oxford Art Online's provides just basic information, while it's a good place to start, it is not considered a research source.
2) Use periodical databases, such as Art & Architecture Source and Proquest, to dig deeper
If you are researching satire in Banksy's art, the two most important words are satire and Banksy.
This is what you'd type in a database search box:
satire AND Banksy