Another technique that I added to my repertoire several years ago is using an old credit card to scrap paint across fabric. I just put blobs of paint around the edges of the fabric and then start scraping the paint and mixing the colors. The results are always serendipitous. I usually finish by dropping blobs of gold metallic paint randomly over the fabric and using a multi-use spreader/scraper from the hardware store to create accents. The first example is on some polyester satin (one of my fabric fabrics to paint on) and the second one is on cotton with one of my desert spirit people silk screened over it.
Recently I visited Claire Benn and Leslie Morgan's web-site and in the pictures of Claire and Leslie was one of Leslie using a credit card to spread thicken dye on the top of fabric. I guess I will be trying that soon. I can hardly wait.
WHAT ARE YOUR FAVORITE TECHNIQUES?