10 Rules for the Creative Sandbox
1. There is no “wrong.”
Which also means there is no “right.” This is play, remember. The point is simply that you’re having fun. 2. Think process, not product.
In other words, It doesn’t matter if you like or hate the product; all that matters is that you’re having fun.
There’s time enough later for editing and crafting. Creative Sandbox time is all about letting your 4-year-old out, and 4-year-olds are much more interested in the experience of creating than in what they make.

How to Bust a Creative Block: Rules for the Creative Sandbox – Melissa Dinwiddie (undated)

Read the full piece for the other eight and rather a lot more.