Adhesion problems with masking tape
Masking tape (and blue painter's tape) is coated with a wax-based release agent in order to prevent the tape sticking to itself on the roll. This release agent must be removed with an organic solvent in order to obtain good adhesion. Isopropyl (rubbing) alcohol is good for this. Acetone will also work, but it is a much stronger solvent (which is not necessarily a good thing).

For blue painter's tape, rub freshly applied tape with solvent until the blue dye starts coming off. Then give it a quick wipe between prints to remove any fingerprints, etc.