Using the right citations is like giving good directions! As a good student and ethical writer, you give credit where credit is due and lead the reader to your sources so they can see you are credible.
Quoting giant blocks of text from different sources doesn't really show the reader your expertise in your topic. This is why people tell you to "put it in your own words" when you are writing, unless the quote is the most amazing quote EVER and MUST be included.
I avoid plagiarism as a writer by reading the information and making sure that I understand what it is trying to say. Then, I close the book and rewrite it in my own words (or switch tabs in Chrome, or shut the computer and write it on paper) Sometimes, I can really remember too much of it, so then I try to re-write my words again so it sounds more like my own and less like I copied it directly and switched out a few words. Then, just to make sure that the reader doesn't think that I wrote this information or made it up, I use in-text citations, or acknowledge the original work in some way in my writing.
Paraphrasing means that you write it in your own words but it's almost the same size as the original piece.
Summarizing means that you read a text and you are giving the reader a shorter version of it.
In-Text Citation guide from Purdue OWL
Seriously, if you learn ONE THING from me, it should be that I like winning arguments on the internet by backing up my feelings with sources that are often from academic journals and peer-reviewed (peer-reviewed is a process where other scholars/professionals/experts look at the work and make sure all the facts are right and the research was done the right way)
http://www.katehart.net/2012/06/citing-sources-quick-and-graphic-guide.html