Make a plan, find the famous places, but after that make sure you have some time
to just stroll along on the banks of the Seine, admire unknown buildings, go into bars and pubs where there are no tourists, and just let the atmosphere of the city allure you, fascinate you, overwhelm you. Breath in the night air of the streets, watch the lights appear on the horizon, feel the joy of being there, the shared joy of everyone who's ever been to Paris, ever been in love, and ever been travelling.