I was commissioned to make a set of 10 "fish" Zentangle Inspired Art cards with 'detailed designs', for twice the normal price, at $10 each.
They all turned out quite different in terms of colouring, although there is a heavy blue theme. 2 are drawn directly onto the cards and the rest are on 'separate' paper pieces, often paired with another colour of paper onto the card background. All blank inside. One paper wrinkled (a lot) with the glue but I managed to save it by drawing in seaweed along the wrinkles... at least the recipient agreed it was up to standard.
I chose to use a lot of patterns that look like scales - things like 'All About V' and 'Archer' and 'Bunzo' and 'DL Sunray' and 'Pineple' worked well. 'Aquafleur' and 'Betweed' were favourite choices for fin and tail shapes. Look these patterns up on www.tanglepatterns.com for ideas and how to draw! I also nearly always used at least two, sometimes three, pen colours - black and white, or black and gold and white, or blue and silver/white, with pencil colours too.