plan out the decal placement 

place decal into water for 5-10 seconds 

remove the decal and let it sit out of the water for 30 seconds to 1 minute 

slide the decal onto the part surface 

position the decal using a toothpick or q-tip 

use a paper towel to remove excess water, and press the towel down to rid as much water as possible 

apply a drop of decal setter and let this sit until it cures, approximately half an hour to a full hour 
spray a gloss clear coat to seal and protect the decal