Drive around find 2-3 LBS. Join their B/C rides. One of them would stand out (speed, people, roads/safety, schedule, etc).
Your local Y or gyms sometime have posting boards.
If there's a big college/university close by, you can peruse students/faculty boards. I'm sure they'll have some kind of cycling club almost always extended to friends and family.
Go ride a busy MUP or popular route. Look for a group you could latch on for while, ask before, stay at the back unless asked to pull (usually doesn't happen until the rest of the group gets to know your group riding skills). Use the water refill stop to find out if they'd be a good match. rinse/repeat until you find the good match.