I firmly believe with enough time and effort you can change from an introvert to an extrovert. However, if you don't do the things in this post daily then you will start to turn back into an introvert. This is a collection of small and easy things you can do to help not only become more extroverted but also help with game.
Trick 1: Compliment people. Compliment them on anything that isn't their looks (men and women). This will also help your game as well. It will help you start to think on your feet if you try to turn this into a conversation. "Hey I like your shoes" "where did you get them?" "If you don't mind me asking how much were they?" Once you start getting good at leading conversations like this you will be able to apply this to game.
Trick 2: Smile all the time. I found this gets me a lot more IOI's and makes approaching easier. Most guys walk around with angry dick head face. If you are the one guy smiling all the time people will notice and want to join you in your happiness. I'm not saying all out dumb grin but raise those lip corners enough were it is noticeable.
Trick 3: (extends on trick 2) Smile at people. If you make eye contact with someone and they don't immediately look away (damn introverts) smile at them. Again not a full faced grin but more than corner of lips raised smile from trick 2.
Trick 4: Do some dumb shit. Walk outside in the morning and scream the first thing that comes to your mind. Lay in the middle of a semi-busy sidewalk. Walk around the stairs through the grass instead of up them. Jump in the air and click your heels. It doesn't matter what you do. This is a key point in breaking your approach anxiety and learning game. Realizing you are a tiny blip in the space time continuum and what you do today will most likely be forgotten tomorrow (apart from rape and murder) is a big step in being more confident.
Trick 5: Say whatever you want (unfiltered). When you walk up to order food say the first comment that comes to your mind. Whether it be about their appearance, the restaurant, or a cool name for your future cat you just thought of. It does not matter. Breaking the filter will open up a world of possibilities when gaming and starting conversations in general.
Trick 6: Amuse yourself. I make myself laugh more than any of my friends. I just walk around and if I think of something funny or notice something funny I will openly laugh about it. It makes you happier throughout the day and helps if you have a pessimistic mindset. This also applies when talking to people in general or gaming. The limits of casual conversation go further than you could imagine. It matters how you say it. If you are saying it in a fact and data type of way (beta) then you will be taken seriously and people will be put off by you. If you sound like you are just amusing yourself and having fun with the conversation people will tend to follow along in your humor.
Trick 7: High five random people. See someone jogging past you. "Keep at it!" high five. Someone says they share the same favorite color as you "I love purple too! High five". Anything anyone says or does that you approve of or amuses you "High five!". There is no sexual expectation or anything like that with a high five therefore 99.99% of people will not look at you weird for doing this. I have done this on dates when I cannot initiate kino naturally, I have done this with people who seem uninterested (instantly interested and happy), and just random people. I have never had it backfire. And if they do ignore your high five? Just high five yourself and laugh it off.
Trick 8: Laugh it off. People are shitty and will do shitty things. You give a compliment and the person looks at you like an idiot. Laugh it off loud enough for them to hear you. Even if it is right in front of their face. It shows you don't care and just want to have a good time. Don't let others bring your mood down.
Trick 9: TALK TO EVERYONE EVERYWHERE. As soon as you get out of bed in the morning talk to the first person you see. Not the second not the third. The first person. Talk to yourself in the mirror if you wont be out for a while. The process needs to start as soon as you wake up so you can ride the wave all day. Standing in line for food? Talk to someone. On the bus? Talk to someone. See someone eating alone? "Is this seat taken?" Talk to them. Male or female it doesn't matter. I've found by doing this and riding the confidence wave of talking to everyone it is way easier to strike up random conversations with anyone, especially women. It changes your entire tone without you having to do anything. It also puts less pressure on the conversation. If you have already talked to 100 people that day then what is one more conversation? It makes each conversation a little less significant and easier to deal with. Really helps with approach anxiety.
Trick 10: I actually got this one on a fortune cookie today. "Those who live without expectations will never experience disappointment." I feel this applies to more than just being an extrovert but TRP in general. The world owes you nothing and you will only get out of it what you put in. Do you wish when you saw familiar faces that aren't friends they would say hi? Be the person who says hi. Do you wish your friends would boost you up randomly without asking? Be that friend that does that. Wish people would randomly enter your day and make you laugh? Be that guy. Don't expect people to do something for you that you won't do for them. Don't expect her to be monogamous if you aren't. Don't expect honesty if you aren't. Don't expect sex on a date. Make it happen. In the wise words of 2 Chainz "I want it so I'mma get it!"
Bonus Tip: Open body. When sitting down spread your legs sit with good posture and keep your arms out. When walking or standing around keep your chest popped out, head up, and shoulders back. DO NOT look at the ground when walking around (unless its steps or something in your way).
These are a few tricks that have helped me come out of my shell and have changed my life drastically. Employ these techniques EVERY DAY and see what happens.