Originally Posted by Bat Guano

One trick I don't think I've seen mentioned here: after you replace a tube, fill it to about 50 - 75% of the final pressure, then deflate it completely. This stretches it into the tire shape, but if there are any pinches, when you deflate they will often resolve themselves, and smooth out. Then pump the tire up to your desired pressure and you should be good to go (barring any other issues, of course).