How to do model railway scenery depends on where your setting your model railway. Ask yourself; is it a country branch line? a city terminus? a loco shed? an industrial area? is it in the mountains? is there a lake? where ever you set the layout will depend on what you need scenically.
For example, a country branch line is not going to need lots of houses and shops, this would be more appropriate in the city or town, additionally if it’s an industrial scene like a colliery your unlikely to have fields of cows and sheep next door.
The best thing to do is to go and look at the real thing or photos, books, magazines etc that’s got you inspired and model that. Be creative with it.