Germany is in a hard place in the middle of Europe. With the right alliance any country but Turkey could conquer her. However, with the right alliance Germany can defend herself. but if you play as Germany you must be exceedingly careful. Almost any ally would be willing to turn on you if your not  strong and defended. Fortunately Germany can be defended pretty easily. The problem comes when you have to exand and defend simeltaneoulsy. To do this you should try to secure one front with diplomacy. It would be helpful to secure your border with France with an agreement but that is unlikely. So you must convince Russia that it would be better to attack Turkey and maybe try to ally yourself with Austria-Hungary. But if it were succesful adding France to the mix as part of your alliance would be great until they run out of major nations to conquer. Then you have to worry about betrayl.

 

Let's go with the likely scenario. You are allied with Austria-Hungary. This means you are not only in a small alliance but you are alone fighting on the western front. You must also make sure that Austria-Hungary is not picked to pieces. One way to do this is to ally with Italy too. If this happens Austria's fronts are down to Turkey and Russia. Furthermore it would benefit you to have another ally to invade France. Now you must play the role of  a bad freind to Austria. You must make sure that Russia will go after Turkey and Austria so you won't have to protect so much on the eastern front. Or yo could try to secure your front with France and go against Russia. This might work beeter because you and Austria could work together. However, always watch your back. If you can manage a safe front and then succeed on the other the game could go quickly for you.

 

Now let's say you are allied with France and Austria. You can choose to focus on Russia or to attempt a naval war with England. If you go with attacking England then you'd want to make sure you don't get tied up in it so that Russia or Austria could just wander right into your country and that is that. If you attack Russia it becomes France and England you have to worry about but it is less likely that it would be as bad if you got stuck in Russia. However, the one thing you must always expect is a French betrayl.

 

In the end to be allied with France would be more profitable but only if you know who your freinds are and that is a little easier if your allied with Austria and Italy.