Make friends with everyone, even students who you would normally never associate yourself with. Since the network of friends in middle school consist of individual cliques, befriending one person in the group can help you gain access to the entire group.
Create exposure for yourself by joining clubs and extra-curricular activities. If you are an athletic-type person, you can join your school's sport team to gain recognition and exposure. You can also participate in school activities to boost your popularity and your name around the school with events such as pep-rallies and talent shows.
Attend middle school functions, such as parties and gatherings. Parties are a great way to meet new people and the atmosphere allows you to relax and be more open to social interaction.
Become friends with other popular students around your school. This may be the quickest and easiest way to join the popular social circle at your middle school, since most popular students are also part of organizations and clubs with high exposure. Popular students are also associated with other popular students and will introduce you to new people.