Key areas:-
Vehicular access
Sight lines
Utility service locations
Planning policy
Established planning precedent
Heights and overlooking / over shadowing

If you can tick many of these then there is a good chance there is potential.

If your property is on a large plot of 1/4 acre or more then again there could be development potential as a total site or an additional dwelling within the curtilage of the existing property.

Selling land can be very profitable and or if it is your main residence it is likely to be capital gains tax exempt.