The key is protecting your front wheel, here is how most crashes happen. Your on a ride with other people (most crashes by yourself are cornering too fast or getting your tire stuck in a rut, hole or road seam) and they slow down and you get tangled up, or they turn without signaling and take your front wheel with them, or you are riding too close and your front wheel gets hung up on their rear wheel. Here is how to avoid it.
Constant focus, looking at the riders ahead of you and adjusting your position to stay safe. If you are going faster and getting close for drafting then don’t follow directly behind, be off to the side 6 inches so if they slow up you will roll up alongside them. If you are approaching a turn give a little extra room in anticipation that the rider you are following might turn or slow down. The better you know the rider and where you are going, the closer you can get. The better you are at braking and anticipating what the group will do the closer you can get.