They will most likely be pretty light overall - it was not until a whole generation had persihed in the trenches and all nations had almost bankrupted themselves in the war effort that all peace treaties become extremely harsh.
If the central powers win:
They'll merge Serbia and Montenegro under a reasonable (read puppet-like) monarch from a junior branch and make the new country a puppet of Austria-Hungary.
Russia will be forces to demilitarise the border, pay large indemnities and clear all the mines they have laid in the Baltic Sea. No Russian naval bases south of the Estonian islands (to ensure they cannot conduct such offensive minings again) would probably be on the table too. I am unsure if Congress Poland would be broken off - probably not, the Germans and Austrians don't want to deal with their own Polish minorities and feel strong enough to not have to.
Belgium will be restored to convince the British to make peace, but in a customs union with Germany and special rights for German traders and merchant navy.
France will probably need to give away some west African colonies, perhaps a little more of Eslass-Lothringen/Alsace-Lorraine and demilitarise the border, including Verdun.
The Ottomans get Kars back from Russia.
Russia will probably experience more turmoil akin to 1905 as they lose another war and will look week. However, the army is not completely eradicated and can keep the revolts down - with blood if needed.
Austria-Hungary and the Ottomans will look strong and can probably keep any minority down without too much violence.
Bulgaria, Romania, Italy and USA will not have time to join the war. The Germans might give the Japanese Tsingtao to buy them off, but will regain other Pacific colonies.