Searching in reference resources first can inform you as to how experts describe the topic you are researching. Many encyclopedia articles cite empirical studies, which can lead you to relevant scholarly journal literature.
APA Handbook of Clinical Psychology
Provides a comprehensive overview of the history of clinical psychology, specialties and settings, theoretical and research approaches, assessment, treatment and prevention, psychological disorders, health and relational disorders, health promotion, educational paths, psychologists' development, ethics and standards, professional organizations, and future directions of clinical psychology.
Corsini Encyclopedia of Psychology
Provides full-text access to an authoritative, comprehensive, and current reference work. Covers all areas of psychology. Articles are signed and contain references and suggested readings. Fully searchable by keyword and browsable by topic.
Databases of Abstracts (Empirical Research)
Your main database:
PsycINFO
This is the premier database for searching the psychology literature. Includes book chapters, dissertations, and other sources in addition to peer-reviewed scholarly journals. Coverage goes back to 1887.
Includes PsycARTICLES journals.
PubMed
Mostly biomedical literature, but searches a fair amount of behavioral science journals as well, especially clinical psychology.
Web of Science
Another large database that searches psychology journals. In the search screen under "More Settings," check only the Social Sciences Citation Index (SSCI) --1900-present.