The main secret of how to make stripes in yard and improving the visual impact of your lawn is having a lawnmower with a heavy roller behind the cutting blade.
It is this rolling of the grass in one direction and then rolling the next stripe in the opposite direction which makes the grass reflect the light in different directions making one stripe appear darker than the other.
The way to make the stripes appear most dramatic is if you keep your grass a little bit longer (so that it flattens better) and the other tip is to use a lawnmower with a good heavy roller to really flatten the grass in each direction.
The problem with having a lawnmower with a heavy roller in it is that it would exhausting to push unless the roller is driven by the engine.
The majority of good lawnmowers with rollers are driven though some of the more expensive ones go one step further by having a ribbed roller- this reduces the roller slipping on damp grass or sloping ground and if you can get one like this it really is a great idea.