I am an amateur 3d modeler for the past 8 years. I haven’t done anything much, most of my work is still in progress. I learned 3ds max by watching and reading tutorials all over the net.
There is one model of mine, which helped me learn most things about modeling by working on it. I am on this project whenever I have the time for the past 8 years, rebuilding several parts along the way as I was becoming more experienced and spotted my “noob” mistakes.
The model is an F104G aircraft. As I went through learning 3ds max, I was able to understand and recreate many difficult techniques, however there is one pretty basic thing that I really want to reach out to more experienced modelers and ask, as it is driving me nuts all these years and still I haven’t been able to solve, making me feel ultimately stupid at times.
I respect all the great rules of modeling ie avoiding trigons and pentagons, adding supporting loops and even mess with crease because I really want to get a model that is an exact representation of the original. I already work on different projects about the aircraft such as the cockpit and ejection seat, all going pretty satisfactorily for a non professional like me.
So, here’s my problem: I can’t seem to achieve perfect edges when opening panels on my model such as a small intake and the landing gear bay. There always seems to be a hard edge poking right at the corner of said panel, outlining an X if you look at the 4 corners of the panels. The model is really where I want it to be right now, I even performed several texturing tests which used to be hell for me, but now i manage it pretty well. I Added detail on the main intakes, and I really am ready to take the model to the next level, IF I manage to solve that edge thing. This is really what is holding me back with other models as well, as I can’t find any rules about modeling that I am violating. So please, somebody help…? I will post some pics as soon as I find out how! 
Major Modeling Issue 3ds Max
It seems that my problem was exactly what I was afraid of. I had to add geometry to the model, so now I have lots of vertices to move around. In an object as big as an aircraft, you will eventually run into an intake or hole of some sort that is too small to model, and too big to solve it through texturing. So I come to the conclusion that such vehicles should be modeled pretty high-poly if a realistic look is targeted. I know it sounds very basic but I always thought that models should be as low poly as possible, and then I started running into hathces, bays, intakes and other stuff like that. Will post pics soon, I kept one that shows it before added geometry, and I will take another one of how it is now.
Models should start low, so you don’t have a ton of verts to move when defining volume and smoothness, the subd modifier will smooth your cage evenly requiring very little geo. Once you have a solid base, subdivide (as necessary, you don’t always need to go over board) and start adding details.
Another approach would be to start low and start cutting details manually, you have to keep your geometry evenly spaced as much as possible or else it’ll turn pinchy and wonky very fast.