If you want to develop a social circle you must decide what you want. Guys or Girls? Or maybe a group of guys to hang out and drink beer, a group of girls to go to clubs and parties and a mixed group to go out together? When you decide what your goal is you can take the apropriate actions. Find a place where you can meet people. From my experience clubs are not a great place to make new friends - it's usually loud and you can't talk much or actually connect with anyone. The best way is to find someone with the same interests. You can go to the gym, or sign up for dancing classes or get involved in some kind of social activity (you will learn new and interesting things and there are many people who will be glad to be friends with you). Since you will be in the same class or group and you're not a random stranger you can always invite them somewhere and they will probably come. After you befriend them it's easy to expand the social circle. Introduce them to new people and let them introduce you to their friends. At that point you will have a choice with who to hang out
Hope this is helpful.PS: Go to the party. Get a drink, go to some random guy who seems friendly and say "Cheers!" or "Hi! What's up?". Then go to another guy/girl and talk to him/her. Just try to talk five or six people really quick and then return and have a longer conversation with some of them. If they don't know each other - introduce them. You will be surprised how friendly people actually are