n preparation of the forthcoming high power campaign with the reactor-relevant deuterium-tritium (DT) fuel mixture in the Joint European Torus (JET), significant efforts are being devoted to DT scenario extrapolation using computer modelling. We report on simulations aimed at optimizing external heating using neutral beam injection (NBI) and radiofrequency waves in the ion cyclotron range of frequencies (ICRF) for high DT fusion yield. Our results show that by increasing external heating power to the maximum power available, the fusion neutron rate can be enhanced by a factor of 4-5 with respect to the recent record values. The comparison of two ICRF schemes using different resonant ion species, i.e. 3He and H minority ions, shows that the 3He minority heating scenario achieves a higher fuel ion temperature but not necessarily a better fusion performance. Finally, we study the dependence of the performance of external heating on key experimental parameters.