That's pretty good for a first go at a new tool! Yet, may I encourage that although you have a tablet, if you want smooth, elegant long curves digitally use beizers. Adobe Illustrator (well, photoshop too) hhas beizers but last I used their beizer system was 12 years ago it was kinda awkward with all those handles. Paint.net is a freebie app so its painless to try and has a much less troublesome beizer/curve system plus other pro-like goodies such as pressure sensitivity, layer support, etc.
Now I did intend for (again) longer curves like your space ship, but freehand and a tablet is still the way to go for shorter, tighter curves and way less time consuming...at least in my experience.