They are not bad i'd recomend useing color's that pop a little more. the color's you are useing don't stand out enough and they make the sigs look monotone. i see that you're duplicating your layers and placing the background overtop of your render then erasing away with your new found abstract brushes. It makes the sigs look like they have a fore, mid and background and eventually leads to adding depth to your sigs. i'd say, doing that coupled with more contrast in your colors between the background and the render will make yours sigs stand out more. Keep up the good work!