firstly the correct fastener with the correct tool should have no issue in tightening... also if you are using cheapo aftermarket boot you would have a poor fastener which will fall off and not tighten up correctly.
the main thing to enusre is that the boot is correct, the boot is seated correctly and the surfaces are clean where the boot sits - generally there is a groove in the cv joint and a rib in the boot these interlink. if you are struggling with cable ties, try pulling with a set of grips, maybe even turn the grips so you coil the cable tie around the grips using the leverage of the coiling and turning moments to assist...
failing that one of these, squeeze and clip... end of.
