The most profitable time to attack France is when you have England as an ally. That's because you and England can launch "diagonal" attacks on the Northwest-Southeast access. Germany isn't usually as good an ally, since it's relatively easy for France to build up an east-facing barrier in Marseilles, Burgundy, Picardy.
You do have to worry about France because it can get two supply centers, Spain and Portugal, versus one for you at Tunis, the first year. Fortunately, England, which gets only Norway, has the same fear. If England can't work something out with France (e.g., to concentrate on Germany), you're his natural ally. In this event, England will derail French expansion by e.g.: F Edinburgh to NS, F London to EC, A Liverpool to Wales, and possibly to Brest or Belgium in the fall of 1901.
So watch out for what England is doing, and be ready to respond in kind. It will take a while, but a successful campaign for you would be Portugal Spain and Marseilles, with England getting Brest, Paris, and Belgium.
For alternatives, I would recommend looking up the answers to this question. I would guess that these occur the majority, perhaps two thirds of the time, and the above, one third.