An expert taught me this way, and it works every time without soap or wetting.
Place decal in position, and take 1 inch masking tape, and make a hinge across the top. you can use two or three pieces of tape, to make sure it does not move. cut between the letters with a knife or scissors, and make each piece individual ones. It is less frustrating working with a bunch of small pieces, instead of one large one. Peel off backing, and squeegee into place from top to bottom, eliminating any air pockets or bubbles. once all is completed, use a heat gun or hair dryer on low heat to seal edges. If any bubbles are present, use a pin to prick the center, and squeegee out the air.