Use the three stripe rule

Manicurists and beauty experts agree that the three stripe method is the easiest and most mess free way to paint nails. To do it, dip the brush in the drop of paint at the bottom of your nail and draw the brush upwards in a straight line through the center of the nail, all the way to the tip. Return the brush to the paint at the bottom of the nail and follow the curve along the bottom of the nail to the left, before drawing a second line, all the way to the tip. Use the remaining polish to draw a third stripe on the right side of the nail.