Your design also needs to consider what you want to achieve from the revegetation. The species you select, their spacings and the planting method will be dictated by the aim of the planting. A total ecosystem restoration will obviously take more resources and planning than an amenity planting with just a few species.
If you are designing the revegetation to conserve a particular animal species, you need to find out the specific habitat requirements of that species. To do this you will need to do some research by consulting scientific or technical literature or speaking to experts and researchers who have worked with that species. You also need to ensure that by conserving one species, you are not reducing the habitat value for other species. Planting a forest on a former grassland could be catastrophic for grassland-dependent species, if there is limited grassland in the area.
Revegetation on the Flerieu Peninsula in South Australia designed as habitat for the Glossy Black Cockatoo
You should also consider the scale of the restoration you are carrying out. If you are restoring at the patch scale (say < 1ha) you need to get the composition and structure of the vegetation as close as you can to what was there before. This means getting as many species into the revegetation as possible, in numbers relative to what you would expect in a representative community. Many revegetation sites are dominated by trees and large shrubs, but in reality, there are only a few of these plants when compared to grasses, forbs and small shrubs in natural communities.
At the landscape scale, it is uneconomic to try to plant every species in the right abundance. As the scale of the revegetation site increases, the variation within the site will increase, creating a mosaic of different plant communities with different composition and structure. These may range from near monocultures, through to restoration with a full suite of species. The composition and structure will also change according to which element is being created or restored (see Elements table). At the landscape scale, a farm forestry plantation can have good biodiversity values relative to monoculture or cleared land providing there are also patches of remnant native vegetation in the landscape (More information).