Not every location is grass friendly, in fact, they're downright difficult. Here's a few tips that might just help you get something growing there where you've had a lot of problems.
Always plant grasses that are most tolerant of the conditions you're trying to establish a lawn. For example, grow shade tolerant grasses in shady areas. Grow warm season grasses in warm season areas of the country.
It's very difficult to plant seed on steeply sloping areas because grass seed should be planted just below the surface. Any water more than just a mist will wash it away. If your only option is seeding the area, make sure the seed is in good contact with the soil. Break up compacted soils before seeding. Use a light mulch or blanket to protect seed during the germination process. Straw, bark or excelsior mulches, paper or fiberglass blankets.
Hydroseeding includes an incorporated mulch that helps, but will not withstand heavy rains / irrigation.
If the budget allows, plant sod or plugs to speed establishment. Sod may have to be anchored to the slope with wooden pegs during the establishment period to prevent shifting during the root establishment period.
Whatever method used, make sure it gets enough moisture without flooding the area. Water slowly so that water can soak in rather than run off.
Most cool season grasses do best in full sun. Fine-leaf fescues are the best suited and Kentucky bluegrass is least adaptable to shady areas.
Sodding is not recommended for these shady areas. Sod is grown in full sun and will not handle the transition to dense shade well and cool season shade tolerant grasses are usually not available.
Once an appropriate seed has been established in a shady area, don't over-fertilize with excess nitrogen. Do maintain adequate phosphorus and potassium. Avoid overwatering. Too much nitrogen and water is an invitation for diseases.
Mow at the highest recommended height for the grass.
If possible, prune low-growing branches from the shade causing canopy to improve light and air movement.
Bad soil can obviously create problems during the turf establishing process. Till compacted soils to a depth of 6" — 8" before planting.
Supply plenty of rotted organic matter to excessively wet or dry soils.
If the soil has a salt content, it may require irrigation to leach the salts from the soil. This will require an adequate movement of water through the soil for this to be effective. Select salt-tolerant grasses such as tall fescue, bermudagrass, or zoysiagrass.
Also read: Post-planting care for SEEDED areas
Also read: Post-planting care for SODDED areas