When selecting masking tape, use tape _without_ the wrinkles. Wrinkled tape can bleed paint and not leave a clean line. The fine line tape is plastic not paper based.

Why is some tape wrinkled? It is so the tape can be run around a corner. ( The wrinkles flatten out on the outside of the curve. ) Plastic tape stretches for the same effect. In a pinch wrinkled tape can be used if you rub the wrinkles flat after application.