Ensure you are using clean distilled water; city water contains minerals that may leave white halos and such marks.
Let the decal dry after application (it will contour slightly) after the decal has had a little time to dry apply a coat of MicroSol or Solvaset.
Apply more water to the model or decal may need to be soaked longer.
Poke the spots with a sharp X-Acto knife, apply a coat of Solvaset or MicroSol (repeat as necessary).
Before applying any decal setting solutions, ensure your model has been coated with a gloss finish. The closer to an automotive gloss finish the better. Cut the decal, dip in warm water and slide the decal off the backing into the model. With a finger and paper towel, or Q-Tip gently roll water out the edges from under the decal. All the decal a little time to begin drying. Once the decal is mostly dry, paint on a coating of your favorite decal solution. We recommend Walthers Solvaset and Micro Scales line of Micro Sol/Set. Depending on the location of the decal, more than one application may be needed.
Important Note:
Once you apply a coat of Solvaset or any decal setting solution do not touch the decal until the solution has dried completely. If you try to touch the decal while a setting solution is on the decal you will destroy the decal.
Ensure you are not using cold water; it is best to use warm distilled water around 80-85 degrees.