Among all of the things that make a lawn look its best, mowing problably is one on the most important.  Keeping your lawn a cut about the rest is really very simple.  The first guideline is mowing height.  A lawn kept clipped at the correct height has more food producing ability, is able to stay greener, reduces weeds, and conserves water by shading the soil.  Weed and crabgrass seed need plenty of sun and heat to sprout.  Because on this, taller grass is one of the best weed preventers you can use.  Shadding the soil by mowing higher also reduces water loss from evaporation.