I don't know if this was mentioned, but once you do get the tire mounted but before adding any air or going around the wheel checking for tire position you may want to check all around between the tire and rim (by pinching the tire's sides to peek into the rim) to make sure the tube isn't stuck anywhere. Keeping a little air in the tube (as much as you can manage and still fit the second side of the tire, really) helps to avoid pinching the tube between the bead and the rim. But a quick check all around on both sides is good for making sure.

I usually perform this check at the same time as I'm running a little soapy water on the bead and on the rim's hook, which then helps me when seating the bead evenly.