Once you've been playing football for a while it becomes second nature. The best I ever done was about 600, but you start to lose focus in your eyes lol. The key is not kicking the ball too hard, just little taps des it. Alternating feet, make sure you can use both feet. Doing it with just one leg will just make it unneccessarily tiring. I played football pretty much all my life up to 16 so you don't really think about it. With a bit of practice you should be able to do it no probs.