Try using a “sludge wash” of artist’s watercolor (sold in tubes), water, and a drop or two of dishwashing liquid. You can clean up the panel with a paper towel (slightly) moistened with water. The water will not harm any of the commonly used model paints.
if you have an airbrush and you haven’t painted the fuselage yet, try preshading. use black to roughly go over the panel lines, nothing too fine, maybe 5 minutes for the whole thing. then when you paint, use lighter layers of paint. worked incredably well for me
Once the acrylics have dried you can put a coat of Future or other clear gloss over the paint. Some colors of Tamiya paint (specifically flat black) are terrible about dissolving when anything is brushed on top of them. The gloss coat will protect them from that, and then you should be able to use acrylic or enamel washes.
Acrylic washes using artist’s acrylics work well, but the surface needs to be very smooth and you should only let them dry for a minute or so before removing the excess. As Danok2 mentioned, artist’s water colors also work very well.
I use an enamel wash on acrylic paints. I paint on a line of black enamel (you don’t have to thin it). Then , when the paint is touch dry, get a cotton swab moistened with enamel thinner and wipe of the excess paint, leaving a line in the panel line. This works best on a gloss finish, and make sure the acrylic paint has dried completely.
The enamel thinner should not have an effect on the acrylic paint. I’ve used Humbrol enamels over Tamiya Acrylics alot and have never had a problem with it. Experiment on a small area first.