Penn's map idea is a good one. Paris is a pretty compact city, and we found many times we could walk from Point A to Point B much easier/faster than taking the Metro. For instance, from Rue Mouffetarde (good outdoor market on Saturday, plenty of inexpensive cafes, for instance La Vieille Tour) to La Bastille, an easy, interesting walk as opposed to taking two metro lines. Very close to Rue Mouffetarde is the Luxembourg garden.
La Vieille Tour Restaurant --good food and interesting decor, pictures here
La Vieille Tour Restaurant they speak English