Just the usual group ride advice. Try to match your cadence to the rider(s) in front of you. There will be accelerations. Hold your wheel until the blood starts from your eye sockets. It's the only way. If you're barely hanging on the back of the line, drop back a length as the old leader drops back. He'll drop in front of you. There will often be a pack reshuffle at left turns or the tops of climbs. If you don't like the wheel you've been on, you might be able to choose a different one. Ride 6" to one side of your wheel, the opposite to what your wheel is doing. Don't get overlap. Maintain situational awareness. Ride smoothly. If they are advertising 22 on the flat, they are going to climb very strongly. If you aren't used to climbing, being a path rider, you need to start doing some intervals besides the one during which you get dropped. If you do get dropped on a climb, do not give up. Hold the same effort as you go over the top and up through the gears in the drops. Good chance they'll sit up and you'll get back on. A few of those and you'll be cooked, but it's good training.