Pro Tip: The Seine as 5th Avenue

(Paris map via Plan de Paris)

When I lived in New York, I took much comfort in the grid system, a concept Paris streets laugh heartily at. Also in New York, I knew that 5th Avenue was as close to a Main Street as we got, since all parallel addresses increased in number the further away from 5th that you went. Luckily, I've learned a little tip about Paris that is equally useful:

Consider the Seine to be your Fifth Avenue. All addresses leading away from the Seine increase in number. (So, right bank: increase northward, left bank: increase southward). Also, addresses running from east/west increase with the flow of the Seine (westward). So if you ever get disoriented or are unsure which direction you're walking when you come out of the Métro, take note of the surrounding addresses and it will (hopefully) help you feel a bit more centered in the City of Lights.