Next step is to add fuselage formers. There are couple ways to do it, I tend to do free-form-spline-way as it allows most control to form. You could also utilize built-in-former definitions but they are useful only if you are doing non-scale plane.
I also tend to use scale positions of formers. Occasionally it results too ‘dense’ structure, but normally original design team has had something in their mind while drawing formers to places specified in factory drawings. So to save thinking I just copy that process.
Using original formers is quite easy if you use most complex way :). This is really curious, as anything easier is actually more complex. Go figure it out. You just import piece of original drawing and draw devfus former around it using control points. All sheeting etc. stuff will come in later stages.
From experience I have found out that there is no point in trying to get too close in this first iteration. Because next I must revert earlier stage and iteratively fine-tune top- & side-drawings. Now I can start peeking 3d-approximation of of design. And then go back and forth. I did tail section formers, next step will be front fuse formers.