When you login to APA PsycInfo, you'll see the Advanced Search screen.
On that screen, it's perfectly fine to simply enter a keyword search to quickly begin reviewing articles on your topic, for example:
However, you might want to explore some of the advanced search techniques available on that page. You can, for example, use dropdown menus on the page to narrow your search.
For instance, you can narrow your search to a specific type of Methodology, such as Clinical Trial, Empirical Study, and others:
You can also narrow your search according to the type of population studied, or the age group studied, in a psychology experiment: