<p>Many physical properties of functional materials are governed by their impurities rather than their bulk characteristics. Defects in crystals can activate electronic and ionic conductivity, create active centres for catalysis or store information through localized spin configurations. Accurate modelling of defect behaviour is therefore essential for predicting material performance and optimizing functionality across a vast application space. However, defect simulations are sensitive to choices made during setup, execution and analysis. In this Perspective, we highlight best practices for calculating and reporting point defect properties through computational methods, with a focus on the widely adopted supercell approach. Key considerations include accurate representation of the structural and electronic properties of the host material, appropriate choice of charge states, sufficient optimization of defect geometries and reproducible calculation of defect formation energies. Adhering to these practices will facilitate robust comparisons between studies and improve the integration of computational predictions with experimental results. We emphasize the importance of reporting computational parameters and correction schemes. Ultimately, an open approach to point defect simulations will strengthen the impact of computational studies and accelerate materials engineering.</p>