Johnston Original Art Dolls

Heya. My name is Kat. I'm new to sculpting in polymer... or... sculpting period. The only thing I did before that was remotely similar was play with playdough and make some little pot type things in my highschool art class out of clay. haha But even considering that I'm pretty happy with my new found ability in sculpting. :P I just ordered some prosculpt off ebay the other day. I'm wondering is it supposed to be so firm? It's pretty firm... and when i pull some off the block of it it just kind of cracks off of it. I'm wondering if maybe it was the heat during shipping... (I live in texas... :( heh) It's workable if I warm it up in my hands a whole lot... but it's really difficult to blend small areas. I've gone through trying to make like 3 doll heads so far and each time I get to fleshing out the face a bit more I end up totally screwing it up just trying to blend the clay in to make it smooth. Before I got prosculpt I was practicing with this cheap sculpey I got at walmart... and it was so soft it was almost like dough (really too soft but still a lot easier to work with). Is there anything I can do to prosculpt to make it softer other than buying another kind of clay and mixing it? Maybe the one I got off ebay is flawed... next time I'll order it off this website... I actually only found this website after ordering it. I haven't been successful making anything with prosculpt yet, but this one I made with sculpy recently :) http://www.moonpaw.com/moonpaw/art/sculpture/Evan_doll_10.jpg