Blisters!

[El Gordo]

I've had the same pair of running shoes for about a year and I got a size bigger because my toenails used to go black and fall off.

If your shoes are a size bigger, that suggests that your feet are moving around in them as you run, which could well be the cause of the blisters. So you need shoes that fit properly.

I don't use Vaseline. Too messy, and it wears off. But it does work reasonably well. I prefer the drier things like Bodyglide. But what really worked for after I had bad blister problems when training for the FLM in 2002, was switching socks. I bought a couple of pairs of Thorlos which are padded and very comfy, and seemed to help me get rid of the blister problem.