Try to work with Fimo (or sculpey, I am not sure it really matters) as well as some super-fine white Milliput. Being water soluble makes Milliput perfect for making curves with nothing but a sponge. On a small sculpture the changes you make should be very subtle, so you do not break the flow of your work. Milliput has a drying time of around 2 hours, but it should be cured for at least a day before any work is done on it
IMHO; you can also set up an epoxy oven if you want it to dry faster, but that usually isn't necessary. Make sure to think 10x more than you sculpt and you should be just fine.
You can blend the two together for a nice mixture of texture. It does get a bit complicated when you get into doing different types of detail.
GS is only good for certain types of work, and even then it should be blended with milliput so you can get maximum use out of it.
I am still relatively new to all of these materials, but the techniques for most "soft" sculpting are usually very similar. Having worked mainly with formal clay, I tend to be a bit rough on my sculpts when working with the epoxies. Milliput is simply amazing for drilling and sanding, so more should be used when you are making things that have hard edges that need to be sanded or carved out.
"Note"
GS is not good at all for sanding or carving, it lacks the stiff nature of Milliput and you can easily tear entire chunks out if you are not careful. It reminds me quite a bit of dried chewing gum, whereas Milliput works a lot more like wood filler.
Have fun

, and try to P.M. some of the sculptors you find on here for more advice if you need it.
Fimo (oven-baked clay)
http://www.artsncrafts-ideas.com/fimo-modelling-clay.php
Milliput
http://www.milliput.com/prod.htm
Get clay-shapers, they are amazing tools; being expensive you should limit your use of them in general. Supplement your tool supply with old razors, and any "medical steel" dental tools you can get hold of. Make your own sponge sticks with some dowels and generic small pored sponges; wrap the sponge onto the dowel and use zip ties to secure it.
Remember that clay-shapers have the black tips, make sure you do not get color shapers until you actually feel you need the extra flexibility.