In my opinion, weathering is best when you pattern it after a picture that frames the subject to reflect the scale of the model. I also believe it is important to think about what would be happening to the real subject to justify the weathering. That is why I think the vast majority of weathering seen on models, mostly plastic models, is unrealistic.
Hold you model at arm's length. Visualize a picture taken of your subject. Find a picture that looks similar. Study the picture and look for weathering patterns. Reproduce and simulate. Also, think about what your model subject normally does or has done recently.
You are greatly helped by this model being a movie subject. Just look over shots of the subject and you are good to go. Remember on this model that the subject flies in space and atmosphere. Smoke and liquids would flow aft. It sits a lot and gets damaged. That would call for paint scrapes and mismatched panel colors.
I would suggest your darker colors be a little more subtle. You can brush over some of your darker areas with a slightly darker tone of the original color to try to lighten the smudges. I would think dark smudges would occur around the edges of panels, to represent maintenance. Those six big ducts on the aft end of the ship probably emitted some smoke, so stains that trail aft and fade would look good. Dark colors in the crevices highlight depth in the model. After you get some dark in there, go back over the higher parts with a slightly darker version of the original color to bring back the depth illusion.
Don't just go dark. You also need highlights. Anywhere there is dark, add a little light. Light colors also illustrate paint chips.
You're off to a good start. Experiment with dark, color, and highlight until it looks right. Try for subtle. You already know something of highlights and shadows from your drawings. Painting these models is no different.