Hi Mike,

> I'm comming from the Polygon/Subdivision-Modelling and
> have very little experience in Nurbs-Modelling.

Check out here for some links to previous discussions with some various tips for people coming from a poly modeling background:
http://moi3d.com/forum/index.php?webtag=MOI&msg=4865.2

One of the biggest differences is that with NURBS modeling you should generally try to focus on using booleans as the main way to do things, and that takes some getting used to if you come from a sub-d modeling background since you usually avoid it for sub-d.

- Michael