The realisation of deep geothermal projects is extremely difficult due to uncertainties in reservoir characterisation, challenges in drilling operations and the complexity of defining stress fields caused by abundant faults and fractures, leaving the significant potential for carbon-free energy mostly untapped. These issues are particularly critical during the planning stages of greenfield developments, such as potential definition, well design and placement, reservoir performance prediction, environmental compliance and concession acquisition. Although not all information is available, a step-by-step, agile project management approach using all physical and numerical modelling possibilities, in addition to systematic data acquisition, is required.