Micro-Scale Decals:
Use only the Micro-Scale setting solutions. They have two. One a pre-set and the other the setting solution. Something like "Solvaset" will burn them up in a heartbeat! Apply a gloss or semi-gloss finish to the model. Wet the area with the pre-set solution. Apply the decal and get it in the right position and try to get all of the bubbles out from under the decal. Then use the setting solution. NOW STOP!
This is very important!
Next, go away and let it dry. You may see the decal start to shrivel. LEAVE IT ALONE! Do not move the decal around. If you do, you'll mess it up. These are very thin decals and it doesn't take much to mess them up.
After the decal has dried and there are no bubbles under it, you can then apply whatever final finish you desire.
Champ Decals:
If you use Champ decals, you can safely use "Solvaset" setting solution. As a matter of fact, the Micro-Scale stuff will probably not be strong enough to get them to hug down around rivet detail.