I don't think the main problem with decals is creating artwork. It's outputting the things as artwork you can transfer to your model (I'm deliberately not saying "decals" because I hope there's some out of the box thinking out there...)
Most of the professional decal designers _I_ know (YMMV, obviously) use Illustrator, because they are creating (in black and white) colour separations for screen printing solid inks. That's not an option for most of us, obviously.
What I'd like to hear is your recommendations, tips and tricks for the right products (eg paper, film, varnish) for printing out home-made decal art.
Especially, my single biggest problem is to find a way to print metal/chrome logos. I have no way of printing silver ink, although I've seen some arty "ink-jet foil" (http://www.craftycom..._FOIL-LAZ1M.htm) which might do the trick but I'd like to hear from anyone who's tried it.
I have both clear and white decal paper, but it's quite thick, especially when you have the varnish layer on it. The colour density on the clear film is very poor, and the white film ends up with a border (if you don't cut well outside the printed area, the ink bleeds when you put it in water to release the decal). I've had some success with printing artwork on clear and applying it over a cut out plain white decal to back it up. That works OK for simple shapes (eg race number circles) but try cutting out a Vargas pin-up nose art for a bomber...
I'd love to hear how anyone manages this without an ALPS printer (and boy, do I wish 1/10th of the effort that's gone into 3D printing had been devoted to a hobbyist 2D printer than can deal with silver, white etc inks...)