The first thing you need to do when looking for articles is determine exactly what you're asking. What's your population? It could be any demographic so long as it's definable. What about that population? Is there a certain date range or location?
You don't need to type all this out when you do a search, but it helps to write it down somewhere. This way, you will have a guide to narrow down your results and fine tune your search.
You have your question, now what? Now we figure out where to look for answers. Think about your topic - who would be writing about that and who would they write it for?
Let's use foster care as an example. A lot of people could write about it - educators, social workers, healthcare workers, psychologists and psychiatrists, community members including foster parents, foster children themselves or former ones. Now who for? All these writers could be writing for others like them or for someone else.
Who the information is written for determines where you search for it. If the intended audience is educators - ERIC, healthcare workers - CINAHL, mental health is PsycInfo, social work is SocIndex, and community members would be periodicals - found in Academic Search Premier.