On cut trails I actually enjoy it. Brilliant for the fitness and it can be very peaceful, especially at night. Just remember heed torch! Thing about cut trail skiing, the ski's are designed solely for them. Very thin and pointless for anything else. If you use fatter touring/back country skis on the trails you'll widen them and piss off the local's.
If you're financially able, buy them, but for an all round package get a set of touring skis and fit them with telemark bindings. You can get 2nd hand tele gear relatively cheap. With that set up you wont (or shouldn't) use cut trails, but then your not restricted to where you can go. Just get a local map and go for a walk, just like you would with an OS and your bike. They're also good on piste. I'm on Rossignol B2's with 7tm bindings and they're brilliant. Good all rounder set up.
As for progression, start off on the flat walking backwards and forwards and you'll find your centre of balance. When moving forward the best tip I got was imagine you are pushing a football with your big toe, not kicking it. Practicing this, you will eventually get the efficient "gliding finn" posture.
If you do start touring about, depending on the gradient you may need to invest in skins. If it's generally flat get some wax.
"every day is a purple day"