Check this out: Courtesy of RoadBikeRider; Sourced By Greg.
---Find the right group. Ideally, it won't be more than 15% too fast or too slow for your present fitness. A big group may need to be split into 2 or 3 smaller ones to accommodate everyone. Pro teams routinely do this in early-season training. The faster group contains riders peaking for the spring classics; the slower one is looking at races later in the season.
---Follow the leader. Every group needs a rider who sets the rules and politely sees that they're followed. Here's a key one: "No one will be dropped except on hills, and then we'll ride easy till everyone is back on."
---Designate the tow trucks. The strongest riders should pull the group together if it splits. For example, the group hits a headwind and 3 riders are dangling at 50 meters. The group slows and 2 strong guys drop back to tow the dropped riders into contact.
---Do more work. If you're a relatively strong rider, get a good workout by spending more time at the front, which gives others a helpful draft. Or, ride to the side of the group in the wind instead of drafting. Help weaker riders up a tough hill with a hand on the small of their back. (Ask first if it's okay.)
---Do less work. If you're concerned about the ride's speed or distance, don't pull at the front. If you do, take very short turns. Get maximum draft. Climb at your own pace on hills. You don't have to go anaerobic trying to stay in contact when you know the group will slow or provide a tow.
Have a Great Weekend. See you on the Road!