Before you depart to France, learn as much as you can by reading guidebooks, on-line guides and blogs. In this way you can make informed decisions about your activities in Paris.
My favorite on-line reference is
Wiki-Voyage Paris. Disclosure, I am a contributor. Wiki-Voyage Paris is comprehensive and written by fellow travelers and locals like me.
Like many Wikis including this one, you can create a personal booklet of 'Wiki-Voyage Paris' to print and stuff in your pocket. I like to mark a printed copy of my destination with notes. During my trip, I make notes about places I visit without defacing a book.
Paris Insiders Guide is an excellent website with many top recommendations for Stay, See, Do, Eat and Drink. Note that your activities will largely depend on where you stay in Paris. :!:Caution, staying far from Paris Center can take two hours on the Metro, round-trip from each day.