Green Field' land that has never been built on may be ideal for multiple house developments, but involve extra costs for sewerage and service connections, etc. for 'one-off' and small schemes.
Brown Field' sites where old buildings have been demolished may need costly clean up, although 'back garden' developments that may be classed as 'brown field' may avoid this.
Sloping land will usually cost more for the foundations and may need special attention to drainage.
Clayey land may need consideration of the expansion and contraction that may take place under wet and dry conditions.
Sandy soils should be checked for the depth of foundation needed to get a solid base.
In all cases a ground and soil investigation should be carried out to check the above conditions along with the level of the water table, natural drainage and chance of flooding.