I think part of the problem is the type of masking tape you use WR.
Blue painter's tape is fine for painting your house, etc. but isn't designed for use on styrene models and other plastics mate. ;(
What you want to use is a masking tape designed for models and forget that crappy "Blue" stuff altogether.
I have used Tamiya masking tapes for years and highly recommend it,
as it has NEVER taken the paint off underneth the tape when I removed it and leaves nice "clean" lines.
It comes in various widths including
6mm,
10mm,
18mm and
40mm.
There are "Other" brands of modelling masking tapes that are out there,
but I can't say I they are as good or better than Tamiya because I have never used them.
Still, you should check out what variety of masking tapes your Hobby Shop has and go for those ones made for models.
Cheers,
Dave