I use dry transfers by Archer and Verlinden every chance I get. They are not as easy to use as decals, but the results are usually superior.
I cut out the transfer, and then tape it in place on the model. I burnish it w/ a piece of metal; usually the blunt end of a sculpting tool, but I've used things like the handles of spoons before. Make sure you burnish the entirety of the transfer really well, or some of it may lift.
They work best if you put them down over matte paint. They don't stick well to flat surfaces like plastic, resin, metal etc.
Getting them to go around compound curves is very difficult. For that application, I would go ahead and use decals instead. If it's a small area, any silvering of the decal can be covered by tiny dots of paint.
Each transfer is usable only once.
A trick I often employ when using DTs is to paint the area of the model the color I want the marking to be, then apply the transfer over the paint. In this way, I use the transfer as a mask; the transfer itself can be any color. I then paint the base color and any effects right over it.
When all is painted, but before I Dullcote, I put down masking tape over the transfer, and use the tape to pull it up. This leaves the original color exposed, in the shape of the transfer.
Helpful?