Dont forget to warm-up first, it is really very important. Try touching the strings lightly at first then if your comfortable, you can now increase the pressure. always use the fourth (pinky) as much as possible, coz its the most relaxed position of the left hand. Unless your doing it on the higher frets, you can use the third. Just continue practicing....your fingers will soon get used to it. :)
Guitarplaying is 1 Percent Inspiration, 99 Percent Perspiration... :)