Remove debris from the area. Rake the steep hill to pick up rocks and branches. If there are weeds, pull them up.
Till the soil to loosen it. Work a tiller to a depth of 4 to 6 inches.
Broadcast grass seed over the steep hill. Use a hand spreader or mechanical spreader, depending on the amount of land you're working with. Walk side to side along the hill to spread the seed. This will keep your from slipping and falling down the hill. It's also easier on your muscles. Use the seed bag to determine how much seed to use per square foot.
Cover the seeds with 1/4 inch of compost or peat moss. This will keep the seeds in place, while also giving them nutrients they need to germinate. The fertilizer will retain moisture in the ground, too.
Apply a small amount of lawn lime over the compost. Aim for a 1/6-inch layer. The lime will boost the soil's pH.
Keep the hill moist until the grass seed germinates. Do not mow until the grass is 2 inches tall.
Prune branches from overhead trees. They may block sunlight from the hill. Grass seed needs direct sun to germinate.
Plant shrubs around the steep hill to control the flow of moisture. Their roots will also help reduce erosion.