Here is the most up-to-date, valuable information on tourist safety - straight from the Paris Police Department itself.
"Prefecture de Police Vous Aider. Touristes: Paris En Toute Securite"
(there is a Translate option)
To the right, under "En Savoir Plus", download the pdf in your native language: French, English, Japanese, Chinese, Korean, Spanish, Russian.
Read it thoroughly and follow the simple recommendations.
There really isn't anything else you need.