I dry sand carfully tne sheet witn a 1000 sand paper before printing.
It flats the surface and helps the ink to grip.
After printing, i use some flat acrilic varnish on a soft brush to fix it.
i dry it quikly with a hair dryer.
It is the quickest and the most efficient way to do stong decals.
I make all instruments ang plugs in the cockpit with decals so it has to be very strong to take the shape of the surfaces.
i use custom decals for many things because with good computer and good softwares wou can go very far in realistic details.
If you want more details on that subject, or templates, i have plenty.
bye