Not sure how universal these painting shops are, but you can go along, pick an item and slap some coloured glaze on it before leaving it for the good people to put it in the kiln for you to collect (often still warm) a couple of days later. I've experimented with a lot of abstract designs but then I started to look at film posters and favourite images from those movies. There are huge limitations with the colours available and the need to paint several coats leaves no possibility for subtlety. Furthmore, the colour you paint on the bisque is about 15 times more pale and less saturated than the end result. You will notice glaring lumps of orange and red in odd places on my tiles - they looked like white with a gentle hint of colour before they were fired. I kinda like the surprise I always get when I go along to collect stuff. Anwyway, with that disclaimer, feel free to look at the ceramic painting page