Practice them using your third and fourth finger with the first as the anchor. I always use the fourth (pinky) for standard riffs but sometimes you may want to hit a higher note that would be impossible if you didn't use the third (ring finger). If it hurts then you're just going to have to practice more, after a few weeks you should have enough strenght in your hands for this not to hurt... then you start on lead and the pain starts all over again;-)