Hi everyone,
Like some users before me I would say that I would totally recommend "Paris pratique par arrondissement". It contains a detailed map of course, and also a directory for streets, as well as all the other kind of maps you would need in Paris: subway, bus lines, etc.
And if you get lost anyway, you can always try asking a local for directions, trust me contrary to popular belief, parisians usually don't bite!
Peace!