Okay, having given it some thought...
Number 1: Have the Germans scrap all plans for fleet expansion as of the earliest possible moment in the 20th century. All potential investments to go into the army instead.
Number 2: Have the Germans, in the knowledge that their colonial empire is a net money drain, offer to sell the German colonies to Britain on the cheap. This removes the perception of Germany as a colonial competitor to Britain.
Number 3: Have the Germans ditch their existing war plans, and have them instead develop an 'East first' strategy for the coming war. Effort must be taken to conceal this plan, up to and including efforts to make it appear as if Germany will most likely pursue a 'France first' strategy. Yet in reality, the plan must be to fight a purely defensive war in the West (never violating Belgian neutrality), and move to knock out Russia quickly.
The goal of these changes is to avoid British entry into the Great War, by removing the two foremost motivations for this, as well as OTL's casus belli. From an outside perspective, the war mostly looks like an Austria-versus-Russia match, with Germany standing by its closest ally, and France stepping in primarily to exact vengeance on Germany (instead of any real desire to help Russia).
I expect the overall result to be a war that ends in a CP victory, in early 1916 at the latest. We avoid the USSR, we avoid the death of multiple monarchies, we avoid Germany being humiliated and bled dry, we avoid Austria-Hungary being cut to pieces, we avoid the Ottoman Empire being dismembered, we avoid the seeds of the British Empire's shameful implosion, we avoid US involvement (and thus the seeds of the USA attempting to be the world's policeman), we avoid a whole generation dying in pointless trench warfare, we avoid the worst of the Great Depression (there'll still be a serious down-turn, but much less dramatic), and avoid Hitler and his goons, too.
Meanwhile, we gain an independent Balticum (a country in personal union with Germany, under the Kaiser), an independent Finland (with a Hohenzollern monarch), an independent Ukraine (with a Hohenzollern monarch), an independent Poland (potentially with a Habsburg monarch because Catholic?) and a defeated French Republic (with seriously good chances of a monarchist restoration).