Requires work and experience. Been doing Ice sculptures for a few years now and every time I do one, I pick up new skills and throw away old experiences. All I can tell you is to start with a good base and also to have a good Ice texture (I have several that I either created or collected over the years) to blend with. One of my favorite filters that I use more then often is EyeCandy 3's Glass filter (free if you click
here). Also, to start the base of the sculpture, I like using G'MIC's Gradient Norm preset. What really requires experience is working with reflections, but for basic ice sculptures, you can skip that step for now.
![Smile :)](./images/smilies/icon_smile.gif)
Below's a link of something that you may like Drac.
http://gimpchat.com/viewtopic.php?f=11&t=921#p9757