  We investigate the effects of the orientation of the magnetic field and the
orientation of a quantum dot, with respect to crystallographic coordinates, on
the quality of an electrically controlled qubit realized in a gated
semiconductor quantum dot. We find that, due to the anisotropy of the
spin-orbit interactions, varying the two orientations it is possible to tune
the qubit in the sense of optimizing the ratio of its couplings to phonons and
to a control electric field. We find conditions under which such optimal setup
can be reached by solely reorienting the magnetic field, and when a specific
positioning of the dot is required. We also find that the knowledge of the
relative sign of the spin-orbit interactions strengths allows to choose a
robust optimal dot geometry, with the dot main axis along [110], or
[1$\overline{1}$0], where the qubit can be always optimized by reorienting the
magnetic field.
