Football Manager 2008

I think the best thing to do would become an international manager, I chose England as they always have a really easy qualifying group and their friendlies are usually sub par. Friendlies do count towards this achievement for international teams, unfortunately friendlies don't count with club teams. Then all you have to do is play through and you should unlock this quite quickly, on the way to 10 clean sheets you will also pick up the 5 clean sheets and single clean sheet achievement. If you are having trouble you can get away with saving the game just before the match and restarting it if you concede a goal. With england I didn't even have to use the save and repeat method.