It depends on how steep and how big an area, but we have had good luck with some of the various biodegradable fabrics. There are some to simply cover the seeds, and there some some with seeds in the fabric.
The hill is so step that if it was damp it was all the Cub Cadet wanted to go up over it. I alteady have a bunch of grass seed, 100lbs. I do have a little bit of burlap but not nearly enough. It is a strip that never had grass on it and the top soil washed off. It probably 15 to 20 feet wide and maybe 200 feet long. I used that dupont seed germination blanket in a area were a lot of water drains. It worked well but was expensive.