What are your interests? Would you find book clubs interesting? Young professional organizations? Church/fellowship groups? Board games? If you have a band instrument gathering dust there are community bands looking for fresh blood. Ditto for community singing groups. Meetup isn't the end-all-be-all; try posting in one of your community's FB groups or checking library and grocery store bulletin boards to see if any events are posted. Sometimes it's just a matter of coming across an advertisement for Group X and seeing if they could use a new member.