When to cite?
Usually, when in doubt you cite. If you're asking yourself whether you should cite a certain piece of information, the answer is probably YES!
Whether the information is written in your words or in someone else's exact words, you still have to cite the information. Even when you rephrase the information to your own words (which is called paraphrasing) you still have to cite it! If you know where information came from, you tell your reader where it came from. It's that simple. Any time something you said has an identifiable source other than your ideas, cite it. Whether it's a direct word-for-word quote, a statistic, a statement you reworded, a fact, or just an idea, you still give credit to where you got it.
If you can cite, you probably should cite!
For a fun look at plagiarism and when to cite things, play the Goblin Threat plagiarism game.