I've been fascinated by this concept for years. I found some pictures of projects that are simply an amalgamation of stitches, motifs and imagination that looked absolutely incredible. Freeform can be knitted or crocheted or both. They start with scrumbles-tiny pieces of knit/crochet stitches. Put them together and/or start adding to it by picking up stitches along an edge and knitting or attaching your yarn somewhere and crocheting. There is no pattern, though you may need templates if your final piece is going to be a garment.
There is no right or wrong to this, you simply use your imagination, yarn and needles or hooks. I'm working on something and it's incorporating knit and crochet. I don't know yet what it is going to be, it hasn't told me yet. But I have lots of tiny amounts of yarn of different weights and looks, along with motifs and pieces of things I've done just to see what they looked like. So, I know it's going to be a large project to incorporate that stuff, but what will it be? Wrap? Afghan? Blanket Shrug? Even I don't know yet. But it seemed like a good idea to put it all together in a showcase of things that otherwise had no use individually.