Blue tape donāt do curves. What I did I found workable is to cut the tapes into strips of 5mm - 10mm wide, then they are easier to conform to the shape of the boot. Then use some more tape to cover the exposed area leaving the area to be paint clear.
For the position and the size, I just eyeballed it using masking tape to do a mock up and take pictures to check against the CRL and game grab screens, before I really go on to the painting process.