Clear coat everything that will be decaled and let dry. Remove all dirt and dust.
Use a saucer with warm water
cut the decal close leaving little clear material
leave in water only long enough to losen the decal from the backing paper
brush a little solvaset thinned with water where you want the decal
place decal on model. I use tweezers and a dental pick
use Q tip to draw excess water between decal and model. you should see the decal suck down into the plastic.
after decal has set slightly you can brush more solvaset onto the top of the decal. use the Q tip to draw excess away. solvaset will melt the deca onto the plastic so use sparingly until you are comfortable using it.
if Q tips are unavailable the corner of a paper towel works just as well to wick away the water but this wicking is imperative to having a good looking decal.