Decals. Well call me old school but I've always tried to free hand my unit markings and such. Decals always felt like cheating and I though tmy painting score would be reduced at tournies. For me decals were always something I used as a kid on model airplanes and such. They looked crappy and always took away from the paint job. I eventually found out that was because I sucked at putting on stenciles.
I recently took up building a Imperial guard force. I decided a lot of character can come out of perfect military writing and symbols. In the past I have alway done things like buy molded shoulder pad for marines or sculpt and re cast them myself. Or stuck to fairly straight forward markings. I've even been known to use stamps or cut my own stenciles for airbrushing. With guard I have rediscovered decals and they can really look good when used correctly.
So after much research trial and error, I give you my decal proceedures to add professional level decals to your models.
Professionally Level Decal Procedures:
1. I always put down a thin gloss coat layer where the decal is going to sit. ( I really like GW 'Ard coat)
2. Decal Solvent is great but you really only have 20 seconds at the most to work with it. You can add about 25% water if you have shaky hands and need a little more time.
3. I usually use cross locking tweezers to hold the back paper. I cut out the decal with scissors but leave a tail to attach the tweezer to the backing, then use the an exacto knife to score the decal so it will slide of the backing, but the backing will still stay in the tweekers.
3. I uses a pencil eraser to move the decal of the backing. It tends to be the only thing I found that won;t stick mark, scratch etc the decal, Sometimes I cut the eraser on the back of a pencil to a little more of a point.
4. Obvious point be use a lot of light, and a clean area... Also was the container you have the solvent in before using it!!! dust is your biggest enemy!!! Also wash your hands. Oil from your fingers can mark decals and can also screw up the solvent and the area you are trying to apply the decal.
5. Use the solvaset or warm water to wet the area on the model (with a paint brush) before you put the wet decal on on it. Makes a big difference when adjusting the decal.
6. Make sure the down side is the side that was on the backing. Both sides of the decal are not the same!!!
7. Put the decal in the warm water for about 30 seconds. This shoudl be enough time to slide it off. If not long enough throw it in for another 10 seconds.
8. Use a paint bush or your pencil to slide the decal off. NEVER YOU FINGERS
9. Use a paint brush to push air bubbles out from under neath out the edges of the decal.
10. Once positioned and air bubbles are removed, sparingly pain the decal remover on top. Make sure you cover the whole decal and edges.
11. Sometimes the decal solvent will make the decal look like it wrinkling. They will usually dry flat. That said if you do start seeing wrinkles a half drop of warm water and a paint brush can straighten out.
12. If the decal dries and you have an air bubble, pop the bubble with a pin, then hit the decal with decal solvent again. It should take care of it.
13. Finish it with a gloss coat. If don't want a glossy finish hit the model with a dull coat (I really like testors dull coat)
That's about as comprehensive as I could make it. I used to use a lot of decals when I was younger with model air planes and I you can really get decals to looks as good as painting (assuming good quality decals).
One note of caution, I never liked red decals, they tend not to work well on a dark backing and for some reason they usually fade to a dark pink. It annoyed me to the point that I started painting the red parts over with red paint...