  The challenging problem of skew scattering for Hall effects in dilute
ferromagnetic alloys, with intertwined effects of spin-orbit coupling,
magnetism and impurity scattering, is studied here from first principles. Our
main aim is to identify chemical trends and work out simple rules for large
skew scattering in terms of the impurity and host states at the Fermi surface,
with particular emphasis on the interplay of the spin and anomalous Hall
effects in one and the same system. The predicted trends are benchmarked by
referring to three different \emph{ab initio} methods based on different
approximations with respect to the electronic structure and transport
properties.
