A word as to colour. One can only give warnings against possible faults;
it is clearly impossible to teach colour by words, even ever so little
of it, though it can be taught in a workshop, at least partially. Well,
I should say, be rather restrained than over-luxurious in colour, or you
weary the eye. Do not attempt over-refinements in colour, but be frank
and simple. If you look at the pieces of colouring that most delight you
in ornamental work, as, _e.g._ a Persian carpet, or an illuminated book
of the Middle Ages, and analyse its elements, you will, if you are not
used to the work, be surprised at the simplicity of it, the few tints
used, the modesty of the tints, and therewithal the clearness and
precision of all boundary lines. In all fine flat colouring there are
regular systems of dividing colour from colour. Above all, don't attempt
iridescent blendings of colour, which look like decomposition. They are
about as much as possible the reverse of useful.
_William Morris._