Best?Practice DFT Protocols for Basic Molecular Computational Chemistry**

Nowadays, many chemical investigations are supported by routine calculations of molecular structures, reaction energies, barrier heights, and spectroscopic properties. The lion's share these quantum-chemical applies density functional theory (DFT) evaluated in atomic-orbital basis sets. This work provides best-practice guidance on the numerous methodological technical aspects DFT three parts: Firstly, we set stage introduce a step-by-step decision tree to choose computational protocol that models experiment as closely possible. Secondly, present recommendation matrix guide choice depending task at hand. A particular focus is achieving an optimal balance between accuracy, robustness, efficiency through multi-level approaches. Finally, discuss selected representative examples illustrate recommended protocols effect choices.