When designing a yard, locate planting beds within the landscape before digging up any dirt. These areas will need to be prepared before you plant anything to improve the soil and create the best environment for the plants to grow in. Cutting in new beds requires some digging and a few supplies.
Spray lines with spray paint to outline where the planting beds will be located. Step back and look at the beds. Make adjustments if necessary.
Dig out grass if there is any located in the planting area, or cover it with dark plastic. If using plastic, stake it down so that it doesn't blow away. It will take at least a week to kill grass with the plastic cover. Blocking out the light will slowly kill it. Dig out the dead sod.
Break the soil up inside the spray-painted lines. Chop it up using a hoe or tiller. This will loosen the soil, add air and allow you mix in other materials to improve it.
Add material to improve the soil, if necessary. Plant selection and soil type determine what amendments are required. If the soil contains a lot of clay, add sand to improve drainage and organic material such as mulch to create a richer top soil. Add enough sand to equal a third of the total tilled soil. If you break up 6 inches of surface, add 3 inches of sand. For sandy soil, till in top soil, mulch and other organic material to to create a richer planting medium.