This is a list of potential predatory publishers and journals put together by a librarian named Jeffrey Beall. Beall’s list is not an all-inclusive or perfect list of predatory publishers, but it is a good place to start. If you see the journal or publishing group on Beall's list, you may want to dig a little deeper.
Cabell's includes both a Journal Whitelist and Journal Blacklist, manuscript preparation tools, and a suite of metrics to help its users find the right journals. The Journal Blacklist is a searchable database of known predatory publishers.
The Committee on Publication Ethics is a nonprofit organization whose mission is to define best practice in the ethics of scholarly publishing. They provide resources and advice for authors regarding predatory publishers and other ethical issues.
Search for the journal or publishing group in the DOAJ. DOAJ is a website "that indexes and provides access to high quality, open access, peer-reviewed journals." Does the journal appear in your search results? If so, you can feel certain it's of high quality.
Think. Check. Submit. is a campaign to help researchers identify trusted journals for their research. It is a simple checklist that researchers can use to assess the credentials of a journal or publisher.