You will often want to draw on the work of others to support your own ideas. Use clear references and citations to indicate from whom the ideas come. But, how do you do it?
Avoid inserting source information without adding your own analysis; instead include your own voice and your own analysis and ideas.
Remember that you will likely want to include sources which are are in agreement AND in disagreement with your own views. This way you can recognize and respond to multiple perspectives on the given issue. In doing so, you can make your own argument stronger.
There are many reasons that writers refer to other people's words and ideas in their own writing; as you write, ask yourself what your reasons are for including each quote or paraphrase.
As background information to help the reader understand some basic information about the topic.
For example, you might quote the health department's statistics on childhood obesity and then paraphrase two reasons that public health experts give for why there is more childhood obesity now than twenty years ago. This would show your reader what the problem is and what current concerns are in general. If you present this information (and cite your sources) without any other comment about the reliability of these stats and reasons, you're telling your reader that you believe these things are commonly accepted background information.
As an exhibit. Think of how evidence is introduced in a courtroom. It may be used as evidence that supports one interpretation of what is true, or it may be shown to point out something important about the person it belongs to. But exhibits are always shown with some comment on what it means.
For example, if a politician says something hateful, you might quote that hateful thing in your paper (and cite it)--not because you agree with what the politician said, but because you want to show your reader some evidence that this person says hateful things.
Another example of an exhibit might be quoting a metaphor from a beautiful poem, in order to show your reader the exact words the poet used, before you go on to analyze the meaning of the metaphor.
As an argument, or set of ideas and theories that you want to discuss.
Remember that as a researcher and writer, your job is not just to repeat what other people have said, but to think about, put together, and make sense of ideas for your reader. Sometimes you may choose to quote or paraphrase someone else's argument in order to compare, contrast, question and analyze that argument.