I would suggest practicing with those you come in contact with.  Talk to the sales clerk (by name), converse with the waitress while she is taking your order and use every opportunity to hone your skills.  I’m not suggesting you “hit-on” everyone you meet, but rather smile, interact, talk and laugh with those around you so you feel comfortable doing so with anyone and everyone (male and female).

At some point it will become more natural and you will feel more confident in your social skills.

SHE SAID:

Let me first say thank you for having the courage to write us. As I read through your question a few times, I think there might be a couple of things going on here. I know most people want to get married one day. And if you have a problem in general talking to people in groups, then finding a mate will be extra hard. First, please know that God made you who you are and it's ok to be an introvert. It's ok to not be the social butterfly, the life of the party, the one everyone flocks to. Praise the Lord for those who watch, listen and observe. They help to balance out the nuts like myself. Years ago I used to pray God would take away my extroverted personality. To make me meek and quiet. Well, after God stopped laughing he said, "Kris, I made you the way you are...but the key is to use it to glorify me." So my first thought for you is to accept that you are quiet and less social and to pray for God to use that for the places He wants. Second, even though I am an extrovert, I am not a big crowd person either. I really prefer small groups where you can talk, listen and really get to know people. So here is what I would do:

1. If you do have to go to a large group social...try and either bring someone with you that you know you can talk to, or make sure someone you know will be there. This is your safety, someone with whom you know you can be yourself. Make sure you pray about the event prior so that God goes out before you and prepares a way. Also know God is with you. Trust in Him to give you the peace you need in these situations. Trust in Him to give you the ability to speak up when it's time and with confidence in the Lord's Spirit versus your own strength. Focus on a table to sit at where there are only a couple of folks. If you don't want to say anything, at least give eye contact and nod to show you are listening. (I have the opposite problem, I have to pray for the Lord to help me shut up!) Remember too to breathe through your nose and outside your mouth to ease your anxiety. Just keep praying the whole time and I promise God will help you. 

2. If you don't have to go to the large socials, then don't. Pray for God to open doors to small socials of 4 or less. If there aren't any, come up with your own. Start with 2 other folks that are like you and go to dinner or a movie. You have two options at this point. You can use these smaller socials as a practicing tool to get you better at talking, listening, eye contact, body movement, interest, responding, etc. OR this could be the best way for you to have a social life, trusting God to bring the right small group of folks together. And this includes bringing a mate to you one day too. It's ok to have a social life made up of 4 people or less. Even Jesus had 3 best buds: Peter, James and John. The solution to being single isn't more big groups of friends but small groups where you can really get closer and care better. Smaller groups where you can learn how to be a friend better, a friend that can lead to a romantic relationship.

Now to deal with the other comment about fitting in. Dont' allow the enemy to make you feel like you have to fit in. God made us with all types of personalities. It's not about fitting in, it's about celebrating your own unique way God made you. Sure, there are some standard behaviors we all should exhibit, like eating with a utensil, using a restroom inside, and walking on two legs. But seriously, what makes you you is you. Why try to be like someone else? You might not have a big group of folks wanting to be like you. Who cares? I don't want to be like anyone anyway. I want to be like Christ. The bottom line is you have to focus on pleasing Christ, not man. Don't look at life as fitting in to the worlds way but fitting in for God's way. Every relationship you have should be about reaching them for Christ. God made you the way you are to reach others.