Generally, for any type of conforming clothing, you're supposed to start with an absolute zero pose on the figure you're making the clothing for. It's even best to use a stripped cr2 where all the morphs, magnets and anything else have been removed. It's not always necessary to use a stripped cr2 but it helps. Then after you've got the item conforming properly, go back in and add the appropriate morphs.

For building shoes and boots for V4/M4, I tend to use a 2-stage modeling process. I build the sock-type structure over the entire foot up to where I need the shoe/boot to be, get that to conform properly, then go back in and pose the foot with the boot in its intended final position, and model the heels and details. Then conform it again.