Hi Dernhelm, Welcome to conceptart. I have only been sculpting for a few years so I won't be as much help as some of the people on this forum, but from my own personal experience it is (and I know this will sound frustrating) a matter of personal preference. However at such an early stage in learning to sculpt I wouldn't worry too much about your creations being spot on perfect as it's not just about the material or the tools you use, it's also about you yourself getting a feel for how you sculpt. The best thing you can do is experiment a bit with the material get a feel for it and have a bit of fun making simple forms and marks with your tools. lumps and bumps can be smoothed out at a later point getting the basic details down first and then building up is something I have always found useful. Remember that most clays are designed to be very malleable and as such do require quite a gentle touch when handling.
On the topic of clay mixing, what ratios have you been mixing your clays to? If the mixture of puppen and classic was too solid did you try changing the ratio so it was slightly softer?
Personally I always use either super sculpey, super sculpey firm or a mix of the two but to be honest I learnt to sculpt in really cheap potter's clay and it gave me a feel for how to manipulate the material without costing a fortune.
Hope this helps and good luck, can't wait to see what you come up with.
Someday I wanna be as good as Andy Bergholtz.