Shoot, shoot, shoot! I have 3 good shooters in my U11s. One girl shoots at 80% plus accuracy, which is awesome. The other two shoot around 60% but have much better circle work and get some awesome long range goals when the defence is tough. 

At training, the three of them spend at least 10-15 mins shooting from different positions in the circle while the rest of the team does other drills. They also do a 10 min shooting warm up before each game. At home, they all have access to hoops and aim to shoot at least 50 goals a day at least 5 times a week. I have also taught them the lying on the ground drill, popping the ball up with backspin so it comes straight back to your hand. 

But from everything I've read (I'm a GD, so not a great shooter!) the main thing is to just keep putting balls through the hoop. Feet and elbows pointed at the net, aim for a witches' hat above the ring, bend knees and finish with hand in periscope position. Adjust and try again and again. Good luck