I would have thought that an obvious lesson France would draw is that it needs friends with a big stick against Germany. That basically comes down to Britain, which is almost certainly going to want to haul Germany back down. Germany dominant on the continent is not in Britain's interests. Germany dominant on the continent is not in France's interests.
Germany's obvious big problem is geography. If Britain is on board, the German coast is at risk; the east needs to be put under pressure. Russia has not proven to be that great an ally, so maybe looking at the likes of Poland, Italy and Turkey to apply pressure on Germany/Austria. I think, by the point, the prospect of separating Germany and Austria are remote.
Internally, there will probably be a period of finger pointing to determine who was to blame, with whoever ends up being able to shift the blame most effectively ending up on top. Toss a coin as to whether that's far right nationalist; far left; highly religious; internationalists; monarchists; military leaders. You might need a coin with a lot of sides.
Since Germany has picked up a number of colonies, the obvious first card to play is that of British twitchiness over threats to its Empire. With Madagascar in German hands, the long route to India is under threat, and Britain will notice. Splitting up Indochina is going to lead to potential for trouble.
Militarily, there are a number of lessons might learn. Germany is likely to stagnate. What they did worked beyond their wildest dreams, and "If it ain't broke, don't fix it" applied then as much as now. France, however, is probably going to start looking for force multipliers of some form.