To me this is part of why the game is fun. It's a challenge. As I play the game more and more (184 hours as of this post), it's quite easy to find my friends. For one, you know they are going to spawn on the beach. All they have to do from there is get on the main road (road with white dotted lines) and read the first white town sign they come across. Then just use a map (like iZurvive or DayzDB) to navigate towards them. To make it even easier, and safer, log into a low pop server to find them.