Always start with a clean surface, widow cleaner and a clean rag!
Then Pray for Jesus to use your hands and guide to entire application to make it be a blessing for all that see it.
after applying many of these decals I did find is much easier to hold the fancy decal facing you and opening/separating the left side (at the L) and removing the top (Decal) half from the bottom blue backing.
Slow is the key word separate slowly
here you only have one go at installing this Decal there is no pulling it off and trying again, Align it up to your liking, firmly pulling and holding Decal flat as you can apply it to the glass or body slowly, top down works for me,
Then smooth over with your hand lightly
Then take a clean towel or cloth and rub gently on all parts of every letter
And again take your towel/cloth and rub gently but firmly smoothing out and rubbing all of the letters again this will ensure full contact