To begin, draw your dots and your border.
Then put your pencil somewhere on the tile (i put mine by the edge of the tile) and close your eyes and draw a string...blind.
i really like this challenge, the stringpart is so important for a zentangle.
i used the tangle i created some months ago: kaurikunda
and the one for which i made the step-out in sept. 2014: yuma
you finde the step-outs on my blog, or tanglepatterns.com
and on the right side you see : trio,created by hanny waldburger, CZT.
trio is one of my favorite tangles, since i know it, i use it almost in every zentangle or ZIA i do. to see the step-out for trio click here.