The Schlieffen Plan was suppose to achieve this by dealing with France first and leaving Russia until later. This was based on an assumption that Russia would take at least six weeks to mobilise, by which time, according to the Schlieffen Plan, France would be knocked out of the war leaving the German army free to concentrate all its efforts on winning the war against Russia.
In order to be able to beat France in such a short period of time Germany had planned to surprise the French forces by attacking through Belgium rather than across the French/German border where an attack would be expected. It was assumed that the Belgian forces would not try to stop those of the Germans, and that the British would not become involved in the war over a ‘scrap of paper’ (the Treaty of London which a number of European countries, including Britain, had signed to ensure Belgium’s neutrality).
The Germans attack on France was also planned to be a very heavy one, with 90% of German forces attacking, the remaining 10% protecting the eastern border from Russian attack. This, Schlieffen hoped would secure a German victory as the German army would be much greater than that of the French.
Using an army that was bigger than that of the French the Germans hoped to be able to trap the French forces in the east and encircle Paris so that they could siege it so the French would have to surrender due to a lack of supplies. This part of the plan was based on the Franco-Prussian, when the French were defeated.
Another part of the Schlieffen Plan was that it was very strictly timetabled, there was a set time for everything to happen so that no confusion could be caused and it could be an easy victory over France.
The final part of the Schlieffen Plan was that the forces planned to use the railways as transport so that troops could quickly move from one placed to another without getting tired out by walking.
All in all the Schlieffen Plan was organised so that Germany could easily win against France by using a mixture of surprise, good planning and heavy attack.