Always use a sharp blade. A blunt blade gives an irregular result and the cut surface of the grass becomes yellow. A sharp blade also uses less energy than a blunt blade.
Do not cut more than ⅓ of the length of the grass. Cut first with the cutting height set high. Examine the result and lower the cutting height to an applicable level. If the grass is very long, drive slowly and cut 2 times if necessary.
Cut in different directions each time to prevent stripes in the lawn.