France is in a relatively easy position. You have immediate, unchallenged access to Spain and Portugal. Furthermore France is very helpful as an ally to its neighbors and therefore can carefully choose your ally. If you see the choice as Germany, Italy, or England then you can choose between the traditional Italy and England, the less common Germany and England/Italy or a country like Russia.

First let's look at the traditional approach, England and Italy, without anyone else. The first thing you should do is capturing Spain and Portugal so that you can immediately start increasing the size of your military. Next you should strike a deal with England over who will control Belgium and Holland. If you can even get them to support you into Belgium it is a success. You should probably go ahead and tell England that Denmark is there's just to make sure your on there're good list. You won't be in need of it anyway. Once you have secured those three countries in your alliance you can commence open war with Germany. However, it is advisable that you make sure Italy is tied up in Austria-Hungary and the Balkans. Now here comes the tough part being able to negotiate with England so that you get the best of Germany and the best chance to get Russia or Austria. If you can do this well enough then you should quickly win.

Now let's go over what an alliance with Germany would mean. This would restrict your ability to avoid fighting on two fronts. You will certainly have to take out England at once. To do this you probably won't get much help from your ally so you might want to wait just a year or so capturing neutral provinces to see if England leaves its centers open. However, you will have to attack quickly if you wait to make sure you don't fall to far back in SC's. If you time the invasion right you should be able to capture England in short time. I highly suggest making it short, because you never want to spend to long but in this case especially because England will be able to protect itself if you don't get enough of their territory soon and then you'd really be in a bad situation. If you manage to overcome England then you would logically shift your attention to Italy but you might think of fighting a faux-war in Italy and be ready to stab Germany if they focus too much on Russia or Austria. This would be much easier than fighting on the always-tricky Italian peninsula. The downside is you would have to find a new ally on the double. I highly suggest not getting yourself in an alliance with Germany.

For the last choice I'll be frank. You'd still have to be allied with England for this and Italy would help to. Russia will in all likelihood have to be stabbed eventually as you will have nowhere to go assuming Italy can take out Austria-Hungary. Otherwise it is essentially the same.

Overall I think the best alliance is with England and Italy and Russia could be helpful additions. The only thing is Russia may ally with Turkey and attempt a sweep and Italy may turn on you so you must be careful. As for allying with Germany that's a brave choice and Germany will get the better deal.