While you are at the beach go down close to the water and make a line somewhere in the sand. This line should be close to the water but not extremely close. Your main focus will be protecting this line.
Imagine the water spliting so it goes around your line. You can also try stopping it before it gets to the line. When you think you have gotten good enough to go closer, visualize the water hitting this line until it actually happens. You can then move closer.
The reason this is best at the beach is because the water is already in motion therefore easier to control. You can try this in still water once you get really good.