Doping by other d-metals in the Co sublattice and/or application of external pressure influences strongly the magnetic properties of 5f-band metamagnet UCoAl. Already 1-2% of Ru or Fe stabilise ferromagnetism, while the doping by Ni as well as the external pressure suppress the metamagnetism. The main role of the observed alloying and pressure effects can be attributed to the involvement of the 5f-ligand hybridisation in both the U 5f-moment formation and the 5f-5f exchange interactions. In many aspects UCoAl shows strong similarities to the 3d band metamagnets CoS2, YCo2 and LuCo2, which suggests an essentially same origin of field-induced phenomena in the both classes of materials.