Literature on Digit Ratio is rapidly growing in Economics. Quite surprisingly we observe that there is no consensus about how to make an accurate measurement in such a delicate task. Along this brief document we offer some concise guidance of how to scan the hands using digital scanners and provide a comprehensive guideline to make a reliable measurement of the 2D:4D. Furthermore, we point out the most common imaging and measurement errors. We also provide a number of hints aimed to avoid these errors that in some cases may cause systematic inaccuracies.