For the fuselage, it’s best to start simply
The body begins as a low poly five-sided cylinder. I locate the Edit Poly Modifier and move the points into a rough fish shape. With some trial and error I end up with something that has a birdlike nose cone and a fin like a porpoise, but it’s very blocky – not to mention asymmetric. Time to apply a Symmetry Modifier, just like I did earlier with the wings.