If you are the kind of person that seems to be naturally introverted doesn't mean that you are destined to spend all of your life watching everyone else around you having all of the fun while you stay on the outside looking in , or just staying at home when everyone else is out having fun. Even though your normal personality is shy there are things that you can do to make yourself look less shy.
You need to convince yourself that you need to make a conscious effort to meet people. You are not going to meet a single person if you keep yourself locked up at home. This doesn't mean that if you go to a party or somewhere there's a big crowd that you have to approach people. Smile and be polite and you'd be surprised to see there might be a lot of people that might talk to you first.
You can start doing this by simply going out to places like bookstores or a coffeehouse. These places might be a little more quiet for your taste and they are places where people do gather and it's a lot less intimidating than if you were to try and go to a really loud party or even a nightclub.
Don't be afraid to strike up a conversation. You might want to start off practicing doing this with people you have met before instead of total strangers. For instance try talking more with fellow employees that you happen to see every day or talk to your neighbor more often than you have in the past. Eventually the idea of starting up conversations won't be as hard as you thought and it might become almost second nature to you if you practice it enough.
You also should consider asking other family members and your friends if they would introduce you to different people they know but you have never met before. Your friends and family probably have a good idea of what kind of people you would feel more comfortable being around. Even though these people will be strangers you will still have something in common and that would be that you know some of the same people. This makes it a lot easier to talk to them when you have something like that in common.
You should also think about all the different things that you are interested in and take those that you know the most about and use them as topics of conversation. This is going to make you feel a lot more comfortable because you'll be talking about something that is familiar.
So some role playing with your friends and family members so that you can practice how to start up conversations on your own with people you don't know. Even though you know your friends and family you still will get use to starting up conversations and they can be honest with you and help you with your approach.
If you happen to be at a party or some gathering, you might want to look for someone who is standing alone and go up to them and try to start talking to them. It might be that they are as shy as you are and they are just waiting for someone to come and talk to them. This will make you feel a lot better and you won't feel as uncomfortable as you would if you were trying to get involved with a conversation with a group of people at a party.
Note: Understand that there is nothing wrong with you being shy, so don't let those who are extroverts tease you or try to make you feel bad just because you aren't as outgoing as they might be.