I will review the computation of the gravitational potential from scattering amplitudes and unitarity. I will also explain how to compute directly observable quantities such as the scattering angle for light or for gravitons passing by a heavy mass (such as a black hole). After this introduction, I will show how to extend our considerations to incorporate higher-derivative corrections to the Einstein-Hilbert theory, in the framework of effective field theories. In the second part I will discuss the prospects of performing computations in Einstein gravity to higher loops using a new, gauge-invariant version of the colour-kinematics BCJ duality formulated directly in a heavy-mass effective theory. As an example I will review the computation of the scattering angle for classical black hole scattering at 3PM (two loops).