I'm pretty new at this but, I think icing consistency is the key. Have you taken a look at the tutorial by antonia74?
I recently made Scooby Doo cookies using tips from her, including her icing and it really made a difference for me.
There's a picture is in my gallery if you want to take a look, not perfect but they came out well. The first one I made, I tossed, emptied my icing bag, thinned it a little more and started over.