Have a party and ask each friend to bring some of their friends. Circulate at parties. Help serve food or drinks rather than sitting on the couch. Hang out in the kitchen at a party. It's usually the center of activity.
Conversation flows easily among the regulars.
Go out for dinner or to a bar on weeknights , rather than weekends. Take a class. Go to your high school reunion and approach your high school crush. Offering companionship to a divorced or widowed acquaintance could spark romance. Volunteer regularly for an organization's programs or serve holiday meals to the homeless.