The primary focus for U12 soccer drills are fundamentals and nurturing the love of the game.  Drills that encourage ball control and creativity with the ball are great.  Make sure players are exposed to a variety of drills as they will quickly get bored with too much repetition.  Station drills and small sided games that expose them to 2 vs. 1, 2 vs.2, and 3 vs. 3 situations can help them start to work on team play.  As a coach you should be encouraging to players and have a teacher's mindset when explaining and demonstrating drills.  To get an idea of a practice plan have a look at our U12 soccer practice plan.