Practice makes perfect my friend. My brother is 24 and still cannot talk to women. I am 27 and have never randomly approached a woman and started a conversation. I always meet women through friends and friends of friends.
Keep in mind, most are just as nervous as you. Try hanging out with a social circle or group that has 1 or 2 females in it. Sit back and listen to the conversation. If one of the girls starts talking about something you are familiar with, when she pauses for a break or finishes her sentence, add something useful to the conversation.
Let's say "she" is Mary and "you" are Bob:
Mary: Did you hear about that new CD coming out by blah blah? I hope it doesn't suck!
Bob: I don't think it will, I read an article in BLAH BLAH magazine and it says it is going to sell millions!
Mary: Oh really!? Did you like their first album?
Bob: Yea, it was pretty good. I liked 4 or 5 of the songs but not all of them. How about you?
Mary: I only liked 2 or 3, which is why i am hoping this album is better.
Bob: Ah, ok, i gotcha.
Just a sample, random, simple conversation. Does not have to be anything amazing, just breaking the ice. Take things slow and keep it casual.
lots of lfie experience