This blog is a great source of up to date information about APA style. It is run by a group of experts who work with APA Style every day. They "publish weekly posts to talk about what we love—writing, publishing, and APA Style" - their words!
For some topics in psychology you might need to consult these additional sources:
There is a vast amount of information on the web relating to psychology but you need to be selective in what you read and make use of. Take care to evaluate the information carefully to assess its quality and credibility. Generally, you should be accessing scholarly, peer-reviewed articles from scientific publications, but some information will only be available via the web. In the Health Sciences, information such as statistics, government policy or strategy, or clinical guidelines for example, will be available from government websites, educational institutions or professional authoritative organisations. Some examples include the Australian Institute of Health and Welfare, the Australian Bureau of Statistics, the World Health Organization, the Australian Psychological Society, or Australian Indigenous HealthInfoNet.