1) Instead of a rectangular or diamond grid, use a grid for which the lines are not parallel. The effective depth of some portions of the shell can be increased so that the shell is considerably stronger.
2) Make small models of surfaces, cut them apart and put them back together in new forms which obtain the desired esthetic and functional result and at the same time are satisfactory from the structural point of view. If the form has valid structural elements such as beams and arches which are properly supported, then the structure will be satisfactory.