Jim,
For decal application I use the following method:
First, I apply (with brush) some decal setting solution (Humbrul Decal fix) onto model surface where the decal is to go. Slide on decal and then press down (gently) with soft tissue paper. I leave for a few minutes, then apply a decal soften solution (Revell decal soft) with the brush supplied in the lid. Again, leave a couple of minutes. Lastly, I get a soft paint (clean) brush and gently brush along decal gently brushing out any bubbles. This also blends the decal into the the surface contours of the model.
Once dry, I then apply several layers of clear coat which, when dry really pulls decal onto surface and blends in decal tone to match surrounding paint.
Dave