Off to a start, but before this comes back to bite you in the "end", fix the part I have circled, in the very least. Cut off the tabs. Make your own with scrap pieces of paper, that way you can line up the endges perfectly.This is is one of those models where everything has to be squared and the angles have to be right on the money. It may be better to cut parts than fold them. You will get an accrued intolerance which will make your model very unsatisfactory to yourself, based on the standard you have shown to us, and that you build at. Even if it means cutting it out and doing it again, it is too primary a feature to leave curved like that. Straight lines, and sharp crisp angles are the hallmark of this particular subject. Some of these spots should be reinforced with balsa wood strips if possible, anything to beep them straight. Color the edges of the parts too. This is where you might think of end result first. If you make a box, which will you see. Should the top of the front panel be visible from the top? Obviously not. Make the top the top, then you only have one edge you have to color in to match up. Any color works, it does not have to be a perfect color, but any color other than white, unless the parts is white, is better. You will have to build the outer box again, or disassemble this one, and remake it absolutely squared up. It will save you much trouble in the end. I follow what you do, I like your builds. I don't offer up critiques unless the modelers is worthy and has shown themselves to be a solid person. The picture I inserted shows how squared, and on the money the lines and angles must be. Each assembly builds on the priors connectedness. In reality, these models are harder than models with many curves, where much can be hid, it is not a simple model to build, and have it look good, that is. The space between the back and front seat (marked with "X") is a bulkhead. That part should be perfectly squared, and go all the way across. It is structural and will make the tube square up, and give it strength. That is why the white space on the floor goes all the way across. That is a part that if you use that tabs, will be almost impossible to make straight. It would be a great spot to stick a wing spar through to help when mounting the wings. You don't have to make these things exactly as they are shown. Plan ahead, Dnalor's thread is a great reference, those his is so big, you can get in it!
Get a good metal straight edge to fold with, and only fold as far as you need go. Symmetry is paramount. The wings will maintain symmetry. mounted to the fuselage, or "body tub" as it stands now. Good time to greeble too!
You cut those parts out perfectly, then somewhere, probably with the tabs, it started going off. Tabs are the bane of modeling. I always cut them off. Take this all with a grain of salt, or start over again, and make each part perfect. you will then want to put the model in a glass case and years from now, you will wonder how you had the patience to make it!
The boat picture which seems to have no relevance is the oldest model that I still have. I made it 24 years ago. It is still straight as an arrow. One of the seats fell out of the topside and got lost during a move, but I will restore it. It also sailed really well, yup, this boat has been on many a pond, and except for the Balsa strips on the sides edging, it is all paper. I used to let her go then go after it in a canoe. It is leaning to the left, 1/8th of an inch, in this picture, but is straight as an arrow. The bow curves up slightly.
