  The recent LHCb angular analysis of the exclusive decay B --> K^* mu^+ mu^-
has indicated significant deviations from the Standard Model expectations. In
order to give precise theory predictions, it is crucial that uncertainties from
non-perturbative QCD are under control and properly included. The dominant QCD
uncertainties originate from the hadronic B --> K^* form factors and from charm
loops. We present a systematic method to include factorisable power corrections
to the form factors in the framework of QCD factorisation and study the impact
of the scheme chosen to define the soft form factors. We also discuss
charm-loop effects.
