Hi Duarte, also if you've previously spent a lot of time doing sub-d modeling in Blender it can sometimes take a while to get used to the very different strategy that you use with NURBS modeling. Basically with NURBS modeling you want to use booleans as a primary way of getting things done, and also try to form most of your model with 2D curves, some 2D curves used for generating things and some for cutting things.

So under regular circumstances a lot of the 3D edges in your final model will be a result of a cutting operation or something like that, rather than all the 3D edges drawn in by hand directly.

One kind of key thing is when you have something that ends in an irregular edge, often times you want to build a more simple initially extended shape and then cut off the end of that piece rather than trying to directly construct surfaces right to the irregular edge itself.

Check out here for some links to discussions and general tips for people who are coming from a sub-d / poly modeling background:
http://moi3d.com/forum/index.php?webtag=MOI&msg=4865.2

- Michael